Any Ideas on Promoting Book Giveaways?

I review books on my blog carp(e) libris reviews and I do book giveaways on about half of them. I promote them through a couple online sweepstakes sites, but so far I've only had luck with two. I also list on a few blogs that promote other bloggers' giveaways, but I'm looking for the most effective ways to announce when I have a book to give away. Anyone else give away books you review? How do you promote them? Also, if you review books on your blog, how do you promote your blog in general? I'd love to hear from you!

I'm interested to hear any answers people have too. I think I'm getting respectable response, since my blog is only about 6 weeks old, but I would definitely love to ramp it up, plus I know I'll have at least one book to give away this summer. There is a blogger's group, too, that might be helpful.

jlcardwell, I should try the Blogger's group as well. I read that one a lot too. I'll tell you what I use: www.online-sweepstakes.com and www.contestgirl.com. I like both and get a lot of hits from those for contests. But others I've tried, I just don't get the response. Books are so subjective - even if a contester wants to win a book, they may not want that one. Hard to find the book audience overall.