Postgenomic now indexes books as well as papers. Currently this is accomplished by examining links to Amazon but there's a more general solution coming.

It turns out that science bloggers link to books pretty often (publishing companies sending out freebies?). At the time of writing there are just over a thousand books in the database, the most popular being the Republican War on Science which is perhaps unsurprising given that Chris Mooney the author is himself a blogger.

I found a couple of interesting books just browsing through the different topic areas - it's quite good fun (all we need now are ratings). The final links to Amazon when you click on a book title on the details page come straight from the blogs that linked to the book in the first place, so any affiliate codes are left intact.