The latest publisher freebie to surface is a .pdf download of Scott Westerfeld's Uglies, a YA novel about a world where you have to be beautiful (I know that place; it's called hell, right?) There are some hoops involved; you have to give them an e-mail address and zip code (but I lied and entered 12345, and the form accepted it.) If you don't want the publisher to SPAM you, be sure to un-check the box on the form.
I tested it out, and was able to download, save and print the book; that's the best kind of freebie. Looks like it'll only be available for 30 days, though, so if you want it don't wait.
Thanks to Paul for the heads up on this.