Interesting idea — What Should I Read Next?. You type in the title and author of a volume that you’ve finished reading and it comes up with suggestions. It’s based, I’d guess, on a collaborative filtering algorithm. It’ll get better with more signed-up users, but it wasn’t very impressive on first attempts. For example, it’d never heard of J.K. Galbraith’s The Great Crash, and produced weird follow-ups for Clay Shirky’s Here Comes Everybody.