I like the idea of forum for the green days and fitbit/exercise monitors (jawbone, iwatch, etc)
The weigh-in one is a good idea if the right amount of people are using it together
If someone starts a weigh-in thread within one of the categories like SW that becomes popular I don't see why I couldn't sticky it for now with the idea in mind to expand on that it in the future.
Thanks for all the suggestions Alison and Millie