What Should I Read Next? is a very nifty tool for getting book recommendations.
Way back when I started cataloguing my books online, I used all consuming, which also had a recommendations feature. Unfortunately, the old version was inclined to be tempermental, not to mention its focus on linking to Amazon. That meant out-of-print or otherwise unlisted-on-Amazon books couldn't be added. My del.icio.us links for this blog tend to be aimed more towards author's own websites, or the publisher's site, because I'm more interested in linking to ideas than to commerical transactions. What Should I Read Next also links to amazon, but the interface seems more simple and elegant.
Also, I was amused that when I fed in Girl With a Pearl Earring, it included Jamaica Inn in the recs. Due to the book meme the other week, I've just reread Jamaica Inn.