I just signed up for Twitter last week and now I'm officially addicted! I'm following a lot of library people and it's a great way to exchange information. Here's my profile!
And I'm also following Henry Rollins, which is cool.
I haven't used Library Thing, but I do use both Goodreads and Shelfari. So I hope those are OK for this exercise! I've been using Goodreads the most lately. Sites like this are great for me because I tend to forget what I've already read, and what I've seen that I want to read in the future. This way I can keep track! Here's my profile and bookshelf.