Thoughts on challenge format

I'm so excited that I've had FIVE people respond that they are interested in doing a weight loss and/or fitness challenge! I think this will definitey be a case of "the more the merrier."

While doing a little research on the best way to approach the challenge, I ran across this website: http://fatbet.net/home.aspx?ReturnUrl=%2fbets.aspx. Is anyone familiar with it? Know anyone who's used it, good or bad?

And to my ladies who are "in" for the challenge. . . . what do you think about using this tool for the weight loss challenge portion? One cool feature I noticed about the site is that keeps your actual weight confidential and only reveals the amount you want to use. You all know that I am very open about my "number," but I realize that not everyone is.

Being relatively impoverished by vet bills currently, I wouldn't be thinking of investing much money in this: certainly no more than $10 apiece, if that!

My current thoughts about the challenge are to have a weight loss portion, a la Biggest Loser, comparing percentage lost each week with a designated weigh-in day for everyone in the group; a fitness portion, where I (or some other group member on a rotating basis) come up with a challenge which must be performed that week (like doing 2 miles on the treadmill and reporting back with a time); and perhaps a nutrition challenge as well (like trying a new/seldom-eaten vegetable or something).

I am totally open to suggestions. What do you all think? (Feel free to weigh in on the format of the challenge--pun intended--whether you want to participate in the challenge or not.)