Livejournal, Mixi, Library Thing, Twitter, Couch Surfing, Myspace, Facebook, Classmates.com, Orkut, LinkedIn, Youtube, DeviantART, Gaia Online, Last.fm, Meetup.com, Diaryland, and Xanga.
I had to check a list of social networking sites on Wikipedia in order to list them all. Sure, some of those I got an account a long time back and haven't touched in years, but others would be nice to keep tabs on without keeping an actual tab open for each!
I tried out something called Tabber, but it doesn't support many of the sites I use. It lets you point directly to a blog URL, but seems to just give those updates as from "Unknown." Plus, Livejournal has friends-only entries, and there's no way to get those in.
Has anyone else found a nice solution? Should I learn more about RSS?