Book recommendations is something I'm always interesting in. At base, all it needs is a feed you can follow just of what people have been reading. I've set up a channel in my social reader called 'Good Reads', and subscribed to Ton's list of books, as the sci-fi focus looks right up my street. If anyone else has a feed of read books, let me know!
I am keeping my own list of books I've read in my wiki - sadly not marked up in any useful way at present - something for me to do there.