Yesterday I got an email from a guy called David, offering to promote my book for free on his site.
I decided it doesn't hurt to look, and I'm pretty happy with what I see.
David will create a page for your book on his site, askdavid.com. It includes the cover image, a blurb about your book (which he will ask you to provide), your photo, book trailer video and a few other details.
Readers can review your book on his page.
You can see my page here.
What does David ask for in return? He appreciates it if you "like" his site (or your page) on Facebook, tweet about it, Google+ it, or give him a backlink on your book's website. Since all of those things help to promote your book as well as his site, it's not a hard thing at all.
His free book promotion page includes tips on how to promote your book for free. It's definitely worth a look.