I don't know how interesting most people find social networking sites, but here's one that you may not have heard of:
my Athlinks profile
I've been a member for a few months. Yes, there are bugs. It lists the OC Marathon as one of my feeds. I definitely did not run that race, nor did I write any of those gear reviews.
Anyway, try searching for yourself. You may be surprised at how they are able to merge all of your race results. As for whether I will really use this, I don't know. I am on Facebook and mySpace already. It would definitely be cool if I knew enough people who would get on this one, though. For now, I will add this to my Links.