Check out Baen publishing. They have a large number of pretty good FREE e-books on their site. They are mostly Sci-Fi and Fantasy action adventure novels but if you are into that, they are one of the leading publishers. I would recommend Keith Lumar, David Drake, John Ringo, Mercedes Lackley just to name a few. Just be warned they are a lot of books that are the first of a series so if you like them you will probably end up buying some books from them too. So it is a good marketing technique.
I have to say that I would prefer to read E-books now. As long as you are not a speed reader, reading on a 3X5 screen is really pretty easy. You can carry around 60 or 70 books on a device half the size of a paper back.
I recommend using a cheaper general use PDA for this instead of a dedicated book reader. I'm finding the Pocket PC Windows to be a pretty good bet. I have not look at a later generation palm so I really can't tell
Any how fire up the browser get over to Baen down load some books put them on your favorite PDA and enjoy.