You can go to the Amazon site and click on the Kindle tab...then over on the right side of the page click on the free stuff, but this is much better... Here is a link that you need to check every day (or even twice a day). This guy puts free books on this blog from the Amazon site as well as off site that can be downloaded into your Kindle. He has the same information on a blog that you can subscribe to (and pay for) through Amazon by the month, but this is his direct webblog address:
http://fkbt.wordpress.com/
I've probably gotten over $500 worth of books free with the help of his site since January. LOVE my Kindle!