One of the podcasts I listen to had mentioned http://dietbet.com, where you can place a wager and split the winnings with anyone in the group that loses at least 4% of their weight in 4 weeks. So, I joined a game with the ItSuxToBeFat blogger & her followers. Today was the first day, but it's not to late to join in. Click here and join our game!
Here's a little more about DietBet if you're curious: