Ems: The "Chicks up for a challenge" subforum (
http://www.3fatchicks.com/forum/chic...challenge-159/) is an excellent place to find weight loss and exercise challenges. Most of them run for a specified period of time, but there are a few that are continuous. It's a very active forum.
If you're serious about losing weight and are willing to stay on track week after week, Sarge's Boot Camp thread (
http://www.3fatchicks.com/forum/chic...camp-11-a.html) is worth checking out. The group is very active and many members regularly post and participate in weekly and on-going side challenges within the thread. It's a great place to get and stay accountable, and regularly challenge yourself, if that's what you're looking for.
Good luck with your weight loss journey, and I'm sure you'll find something on 3FC that suits your needs!