Lately, I get so many invites on various social networks, that its becoming a part time job, just responding to the various stupidity. Most of the friend requests are from people I don't know and who don't know me. I often respond, "How do I know you?" I get three follow-ups from there.

1. Don't you remember me, we use to do this and that?
   I immediately add this person as a friend.
2. No response ever.
   Obviously a social network spammer who is crawling friends of friends and adding just anybody they can to boost their friend count.
3. We are connected in LinkedIn.
   Another social network spammer. This person is not only adding just anybody to one social network, but then they are importing contacts across their social networks.

Here's some rules that I follow.

1. I only originate a social network connection when I truly know the person or have reason to contact the person.
2. I'll accept invitations on LinkedIn from just about anybody (as long as your profile looks reasonable). I do this because I'm in the Internet business and being nice to other people on the Internet is only smart business.
3. I'll accept invitations on MySpace from just about anybody. I do this because I occasionally write MySpace layout codes and want to encourage adoption.
4. I won't accept invitation on Facebook unless I really know you. I do this because my real friends actually use Facebook and its the one true social network that works for connecting me with my friends.