[724Skinsfan]

I think Facebook's strongest aspect is the Groups feature. We have a trail runners group of about 200 people that share race info, training schedules, medical issues, nutrition, etc all on a local level. I also post my Runkeeper activities because a few people told me it keeps them a bit motivated to go out and run when they didn't want to that day.

However, if you have to start paying for anything then I'm out.