My Facebook friends and Twitter follows, whether they know it or not, are helping me lose some weight!
The short of is that I hooked up my fridge to my Facebook and Twitter accounts to post whenever I try and snack late night before going to bed. Not exactly a healthy habit that I have. But just by knowing that everyone I know will know when I'm trying to raid the fridge at night has really started to help me with that.
I have a tumblr page setup for it:
Also, I have an instructable up if your interested in the specifics of how it is put together, with code.