Every week or so I update my contacts; I check Facebook, Flickr, Twitter, LiveJournal, LinkedIn, FriendFeed, Plaxo and GigPark. (I also check Last.fm once in a while but it still says the friend finder feature is “coming soon”.)
I use the different services in different ways, e.g. Facebook is for people I’ve met IRL whereas Flickr is anyone whose work I find interesting. I have four main groups on Twitter: people I know; people in my industry (Agile project management); photographers who give out handy tips; anyone else I’ve stumbled across that seems interesting … but I also try to keep the number of people that I follow to a manageable level (250-300 people) so that I can actually read what people say rather than just watch it scroll past.
So if you’re on one of those and I’m not connected to you, friend me! My contact info is @ http://www.paulhenman.me/ or drop me an email so I can add your contact info to Gmail and then I’ll find you on each of the services I use.
Oh, and if there’s a really neat social networking site that I’m missing, let me know or send me an invitation to join – I try to check them all out but many have fallen by the wayside.