I just stumbled across AllConsuming.net, which looks like a pretty innovative site... it scans weblogs and looks for links to books on Amazon, Barnes & Noble and other book sites. It then relates them all together - look up a favorite book to find other blogs that have linked to it (sorted by date, too, in case it's very topical), which seems like a great way to find new bloggers. For example, see who else has pointed at one of my favorite tech books.
I wonder what the criteria is for selecting the blogs. I wrote a review of this book for Slashdot.org (http://books.slashdot.org/article.pl?sid=03/11/19/1333258&mode=nested&tid=133&tid=186&tid=187) yeah, gave it a 10, it's really good, and this engine misses the review on Slashdot, with explicit links to BN.com and all.
Alex: I'm not sure, perhaps Slashdot isn't considered a blog since it's not the traditional type, more of a web forum with an RSS feed. Why don't you try mailing the author and find out? -->
Send questions and suggestions for improvement to erik at allconsuming dot net.