For my fellow Kindlers, this is a list of places where you can get tons of books for your Kindle absolutely for free.
18,546 free books including both classics and non-classics
Non-classic free books for Kindle
Of course, there is also Project Gutenberg that has almost 30,000 free books in its catalogue. The problem with Project Gutenberg books is that often they are transferred onto the Kindle in a very weird formatting style that makes them hard to read. But there is a way around that (that doesn't involve any complex downloading of weird programs and having to do any formatting yourself):
On your Kindle, type the following url: http://tinyurl.com/gutmagic. Then, download the Magic Catalogue (MOBI Edition). This will onnly take a couple of seconds. Once you have the catalogue, you will be able to download ANY Project Gutenberg book directly onto your Kindle and in a format that is a pleasure to read.
For my Kindle-related information, I usually go to the following places:
A Kindle World Blog (always has the best information sooner than anybody else)
Kindle Community's Advice on Free Books (this discussion thread seems endless but it has tons of great information)