I'm loving Goodreads. You can find me there, as well as many other League members.
It's a social networking site just for readers and authors, where I can be a fanboy and leave comments for my favorite authors and lurk around book clubs discussing Palahniuk, Sedaris and Gaiman. I do think it's funny that the site doesn't distinguish my name from all the other writing Mark Henry's, so it looks like I'm quite prolific in things other than zombie porn. Genre's I'd never think of touching, particularly westerns, cuz...no.
A warning for thin-skinned authors: Goodreads is such a good site because the members review books with abandon. I've been skewered, then praised. So have you.
Whatevs. It's a great place to keep track of reading habits and meet people with similar tastes. You should totally check it out. Friend me while you're at it. In fact, friend all the League folks!
What's your favorite site?