ACB's options are the best thus far. However, I would add the following:

FLASHBACK: If this appears, the contestant's winnings will increase or be reduced to one of the offers they received during the game. When opened, the placard would read FLASHBACK >> 4TH OFFER or something to that effect.

I'm Mad Mark, and I approve this message.

why does anyone need to approve their own message

this message was approved by gordon ramsay

I just thought of another idea for Box 23. It could contain one of these 10 options:

Good Options:

QUADRUPLE
DOUBLE
+£20,000
+£10,000
+£5,000

Bad Options:

MONEY BACK
HALF
QUARTER
10%
NOTHING

During the usual Box 23 explanation, the player will choose 2 good options and 3 bad options at random for Box 23, using two bags of balls with the options hidden inside the balls.The adjudicator will then choose one of those five options at random to be Box 23's contents. The contestant will find about the five options for Box 23 immediately after the last box of the main game is opened.

This will solve virtually all of Box 23's flaws, and will make it possible (though EXTREMELY unlikely to the point that Channel 4 won't have to worry much about it) for Deal or No Deal to create a MILLIONAIRE.

I think this

Triple
15,000
Money Back
One Third of winnings
5 %

Any new ideas?

The only problem with that is that nearly everyone who purchases Box 23 and finds that in it will join the THIRD OF A PENNY club (as none of the blues bar £750 are divisible by 3).

Triple
15,000
Money Back
One fifth of winnings
5 %

Good?