Okay I definately know of 4 challenges going on and I'm definately in on three.
The bun challenge, where you hair in a bun for a year (okay, I haven't been doing it for a year, but I wear my hair up 5-7 fays a week) this challenge started in August.
The Product challenge. You cannot buy another hair product until the end of December. I joined this because I am trying to use up the stuff I have before I get a lot more stuff.
The hydro challenge. Boost your intake of water.
The V-challenge. This thread is hot right now, so you'll be able to read about it easily.
Oh there is another one. The protein challenge. Try to get a lot more protein in your diet.
Okay those are all that I can remember!