What % of friends on Facebook are friends?
makecheck: I'm not sure how good an indicator the overall count is.  For one thing, you might not even find everyone you know on Facebook.I figure there are two ways to use these sites.  One, you could connect with everyone you've ever known, regardless of how well you know them (and end up with 300 "friends", most of whom are really just "acquaintances").  Or two, judiciously invite the people you actually care about and/or are likely to see anytime soon.  I choose the latter, whether it's Facebook or other sites like LinkedIn.With a short list, it's easier to find the people you're likely to want to talk to in the near future.  Plus, you then receive only limited spam about the mundane details of other people's lives. :)