Stumbled on this on Lifehacker today (though they seem to have been overwhelmed by the attention- servers are currently offline):
YourNextRead Tells You What Book You Should Read Next
from Lifehacker by Jason Fitzpatrick
If you're looking to stock your summer reading list YourNextRead is a simple and crowd-driven tool for finding out what book you should read next based on the ones you've recently finished. Tell YourNextRead what book you just finishedand enjoyed!and it will generate a web of eight related books. You can click on any of the books to learn more about it which will, in turn, generate a new web that's based on that book. Alternatively you can use the thumbs up/down buttons to agree or disagree with the suggestions that YourNextRead gives you. Each suggestion includes Amazon rankings and ratings and a link to purchase the book on Amazon. You can use the service without logging in but signing up for a free account enables book-browsing history and wishlist functionality.