Launched in 2006 and, I think, mentioned here for the first time, BookGlutton has put 1,660 books online and created tools that let readers form groups to discuss their favorite titles. From the site:
"We believe firmly that people want to read, annotate and discuss, right there, immersed in the text. That’s the best time to talk about a book. We also respect the solitary side to reading: people should have the chance to tune out the community. We wanted it to be attractive, too; to be an experience. It was designed for the laptops people carry to their coffee shops, and meant for the network, not the desktop. Finally, it had to be something we’d want to use. Naturally we’ve got a list of improvements. Like any creative endeavor, we’re always seeing new ways to tweak it. And we’re open to suggestions! You can suggest features or give us general feedback."