Other rules and laws of Twenty 20 cricket are designed to make Twenty 20 cricket more exciting and add to the 'fun' factor of a typical Twenty 20 cricket match. 

Rules of Twenty 20 cricket- Rules to make Twenty 20 cricket more fun 
Here are some rules of Twenty 20 cricket to add to the carnival cricket atmosphere

Special Twenty 20 cricket rule 1: The Free Hit 
An interesting rule of Twenty 20 cricket is the Free Hit. This Twenty 20 cricket rule states that following a no-ball as a result of overstepping, the next ball shall be a Free Hit. For this ball,the batsman is not given given out by any way in the cricket rules apart from being run-out.

Special Twenty 20 cricket rule 2: Power to the umpires
A controversial rule of Twenty 20 cricket states that umpires may award five runs to one of the teams playing the Twenty 20 cricket match, in case the umpires feel that the other team is needlessly wasting time. This Twenty 20 cricket rule is obviously controversial because of the recent ruckus over the Inzamam-Hair incident. One just hopes that this rule of Twenty 20 cricket does not lead to more cricketing controversies

Special Twenty 20 cricket rule 3: Twenty overs within 75 minutes
This Twenty 20 cricket rule imposes strict penalties on bowling teams not completing their alloted 20 overs within 75 minutes. As per this rule of Twenty 20 cricket, a bonus of 6 runs is awarded to the batting team in case the bowling team does not begin their 20th over before 75 minutes. This rule of Twenty 20 cricket is intended to be strictly imposed since completing the Twenty 20 cricket match within 3 hours is one of the primary benefits and selling points of Twenty 20 cricket.

Special Twenty 20 cricket rule 4: Bowling restrictions of Twenty 20 cricket
This rule of Twenty 20 cricket once again emphasizes that the laws and rules of the cricket game are becoming more batsman-friendly at the expense of the hapless bowlers.

This bowler specific Twenty 20 rule states that bowlers can bowl a maximum of 4 overs- limiting the individual impact of bowlers on the outcome of a Twenty 20 cricket match. 

Special Twenty 20 cricket rule 5: Fielding restrictions of Twenty 20 cricket
Twenty 20 cricket rules state that only 5 fielders can field on the leg side at any point of time. This rule of Twenty 20 cricket is largely inconsequential these days as the bowlers typically tend to set a more balanced field on either side of the wicket. 

This particular Twenty 20 rule impacts perhaps only off spinners who sometimes prefer to have 6 fielders on the leg side as the direction of the spin implies that batsmen will prefer to play on the leg side.

The other fielding restriction rule of Twenty 20 cricket states that a maximum of two fielders can be outside the ring in the first 6 overs and a maximum of five fielders can be outside the ring for the remaining 14 overs. This rule of Twenty 20 cricket is quite simple and similar to the fielding restriction rule of one day international cricket. 

Special Twenty 20 cricket rule 6: Bowl-outs
This special Twenty 20 cricket rule applies to Twenty 20 matches that end in a tie. This Twenty 20 cricket rule introduces the novelty of a bowl-out to decide on the outcome of the Twenty 20 cricket match.

According to this Twenty 20 cricket rule, five bowlers from either team are allowed to bowl two balls at the wicket with no batsman at the crease. The Twenty 20 rule states that the maximum times the wicket is castled by either team decides the outcome of the Twenty 20 match. This Twenty 20 cricket rule, borrowed from other sports such as soccer, adds to the excitement of the spectators.

However, a novel Twenty 20 rule similar to the 'Golden goal' or the 'extra time' concept of soccer or basketball would probably make the end-game of a Twenty 20 cricket match more interesting. 
 

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The file below is the detailed Twenty20 Cup rules and regulations from the 2005 
First Class Regulations and Playing Conditions:

1 Playing Conditions
The Playing Conditions for First Class Cricket as they
relate to matches in The County Championship will
apply, with the following exceptions:
2 Duration
The matches will consist of one innings per side, each
innings being limited to a maximum of 20 overs.
Two days will be allocated for Finals Day in case of
weather interference. There will be no reserve day for
Group League matches.
3 Hours of Play and Intervals
3.1 In all matches without a Reserve Day
(Group League matches and quarter-finals)
Standard Scheduled Start and Cessation Times are as
follows:
First Session .......................................5.30pm - 6.45pm
Interval ................................................ 6.45pm - 7.00pm
Second Session ................................. 7.00pm - 8.15pm
Note Start times may be altered with the approval of ECB
3.1.1 Interval Between Innings
If the innings of the team batting first is completed prior
to the scheduled time for the Interval, the Interval shall
take place immediately and the Innings of the team
batting second will commence correspondingly earlier.
In circumstances where the side bowling first has not
completed the allotted number of overs by the
scheduled or re-scheduled cessation time for the first
innings, the umpires shall reduce the length of the
interval by the amount of time that the first innings overran.
The minimum time for the interval will be 10
minutes.
3.1.2 On all occasions where play is delayed or interrupted the
Umpires will reduce the length of the Interval to 10
minutes.
3.1.3 Intervals for Drinks
No drinks intervals are permitted.
3.2 Finals Day
3.2.1 Both semi-finals and the final will be played on Saturday
7 August (Reserve Day Sunday 8 August). The
scheduled hours of play will be as follows:
First Semi-Final
First Session ....................................11.30am - 12.45pm
Interval ............................................12.45pm - 1.00pm
Second Session ................................1.00pm - 2.15pm
Second Semi-Final
First Session....................................... 3.00pm - 4.15pm
Interval ................................................ 4.15pm - 4.30pm
Second Session ................................. 4.30pm - 5.45pm
Final
First Session ....................................... 7.15pm - 8.30pm
Interval ................................................ 8.30pm - 8.45pm
Second Session ............................... 8.45pm - 10.00pm
3.2.2 The Chairman of the Cricket Advisory Committee will
appoint a Technical Committee who will in conjunction
with the Umpires, determine the re-arrangement of
overs and timings of matches in the case of any match
being delayed or interrupted. At all times, the
objectives of the Technical Committee will be
prioritized as follows:
l To ensure that both Semi-Finals and the Final are
completed on the scheduled day of the matches
(minimum overs to constitute a match is 5 overs per
team).
l To ensure wherever possible a 20-over per side
floodlit Final
l To ensure that wherever possible both semi-finals
are of the same duration
l To ensure that wherever possible, within each
match, teams have the opportunity of batting for
the same number of overs.
l To balance the desire to achieve commercial
objectives with the need to ensure matches of as
long a duration as possible
In making its judgments, the Technical Committee will
need to take into account the amount of play that may
already have taken place, the amount of play
remaining, and the most accurate weather forecast.
If there is a delayed start or one or more interruptions
in play, the Technical Committee may order up to 30
minutes of extra time either at the break between the
first and second semi-final and/or between the second
semi-final and the final and/or at the end of the first
day (latest re-scheduled finish 10.30pm) and readjust
the timings for matches as appropriate. If the
Technical Committee is satisfied that the Final cannot
be completed on the first day, the timing for cessation
of play on the first day will be 10.00pm.
The available hours of play on the Reserve Day are
10.00 - 8.00pm. No floodlights shall be available on
the Reserve Day. The Technical Committee will
schedule play on the Reserve Day in order to maximise
playing time.
3.2.3 There will normally be two sessions of play of 1 hour
15 minutes each, separated by an interval of 15
minutes. If the innings of the team batting first is
completed prior to the scheduled time for the interval,
the interval shall take place immediately and the
innings of the team batting second will commence
correspondingly earlier.
3.2.4 On any occasion where the innings of the side batting
first is delayed or interrupted, the Umpires will reduce
the length of the interval to 10 minutes.
In circumstances where the side bowling first has not
completed the allotted number of overs by the
scheduled or re-scheduled cessation time for the first
innings, the umpires shall reduce the length of the
interval by the amount of time that the first innings
over-ran. The minimum time for the interval will be 10
minutes.
3.2.5 No drinks intervals are permitted.
4 Length of Innings
4.1 In uninterrupted matches (ie. matches which are
neither delayed nor interrupted):
4.1.1 Each team shall bat for 20 overs unless all out earlier.
4.1.2 If the team fielding first fails to bowl the required
number of overs by the scheduled time for the
cessation of the first innings, play shall continue until
the required number of overs has been bowled and
Playing Condition 16 shall apply.
4.1.3 If the team batting first is dismissed in less than 20
overs, the team batting second shall be entitled to bat
for 20 overs.
4.1.4 If the team fielding second fails to bowl 20 overs by the
scheduled time for the cessation of the second
innings, the hours of play for the match shall, subject
to conditions of ground, weather and light, be
extended until the required number of overs has been
bowled or a result has been achieved and Playing
Condition 16 shall apply.
4.2 Delayed or interrupted matches - Group
Stage Matches.
4.2.1 Any revision of the number of overs that may be
necessary due to a delayed start or one or more
interruptions in play as a result of adverse ground,
weather or light conditions or any other reason, shall
only be made on the final scheduled day of the match.
4.2.2 Delay or interruptions to the innings of the team
batting first.
(a) When playing time has been lost (see above) the
revised number of further overs to be bowled in the
match shall be based on a rate of 3.75 mins per over
in the total remaining time available for play. When
calculating the length of remaining playing time
available for the match the duration of the interval
between innings will be taken into account.
Should calculations regarding numbers of overs result
in a fraction of an over, the fraction shall be ignored. In
the event of a suspension occurring in the middle of an
over, the number of total overs to be bowled in the
match will be calculated as if the over in progress at
the time of the interruption had been completed. The
innings of the team batting first will continue from the
point of the interruption.
The revision of the number of overs should ensure,
whenever possible, that both teams have the
opportunity to bat for the same number of overs.
(Where this is possible, if the total number of overs in
the match thereby calculated results in an odd number
of total overs in the match, then one over shall be
added and the new total divided in half).
(b) The team batting second shall not bat for a greater
number of overs than the first team unless the latter
completed its innings in less than its allocated overs.
To constitute a match, a minimum of 5 overs has to be
bowled to the side batting second, subject to the
innings not being completed earlier.
A fixed time will be specified for the commencement of
the interval, and also the close of play for the match, by
applying a rate of 3.75 mins per over in respect of each
over already bowled and/or scheduled to be bowled in
each innings. All relative delays, interruptions in play,
and the duration of the interval will be taken into
account.
If this calculation produces a close of play time that is
earlier than the original time for cessation of play on
the final scheduled day for play, then one additional
over should be allocated to each team, with the interval
and close of play times being recalculated accordingly.
If there is more than one interruption to the innings of
the side batting first, the above calculations should
always be based on the original scheduled close of
play, rather than the rescheduled close resulting from
the previous interruption.
(c) If the team fielding first fails to bowl the revised number
of overs by the specified time, play shall continue
subject to conditions of ground, weather and light until
the required number of overs has been bowled or the
innings is completed, and Playing Condition 16 shall
apply. In all reduced overs matches both teams will be
given one over's leeway in addition to any time that the
Umpires might allow for stoppages. Allowances prior
to a stoppage are carried forward for the purposes of
the application of Playing Condition 16 only - they do
not influence the recalculated number of overs or the
scheduled close of either innings.