Facebook is one of my biggest hobbies. I’m pretty much always online.
Dictionary.com is another big one. I keep it on my ipod and am always checking out the meaning of words. It’s great for “older” books and doctrinal studies.
Goodreads is where I keep track of the novels I read. Bookworms are the best people.
Clio is the blog of a very close cousin of mine. He’s a bookworm too. =)
WordPress, obviously.
I love dictionary.com. I use it all the time. =]