I'm trying to recruit friends to participate in Infinite Summer — reading David Foster Wallace's Infinite Jest between June and September. The friends of mine who have read it have raved about it, and it sounds like a lot of fun to read such a massive tome with people all over the world.
You can visit the web site to share your thoughts and read what others have to say (or not), and follow Infinite Summer on Twitter. I think they're also on Facebook, but since I no longer have an account there, who knows. The official dates are June 21 to September 22 (the period of summer), but according to Twitter, some people have already started.
I still have to finish three books (The Historian, Everything Ravaged, Everything Burned, and The Gastronomical Me) before I can start this one, but as you only need to read 75 pages a week to keep on schedule, it doesn't sound like it will be too hard to read other things at the same time.