Since November 16th 2009, MoneyGram has been running a contest that will see a winner each week having their sent money doubled. All you have to do is send money and gain yourself an entry in the draw.
This is what's written on their website:
We've been searching for a fun way to show our appreciation to everyone who chooses MoneyGram. Then it struck us. Just send money online between November 16 and December 20, 2009 and if you're selected, we'll double your send. Winners are chosen weekly, so send money today.
No Purchase Necessary. You may also enter by following instructions in the Official Rules.
That's it! All you have to do to Double Your Send