Doreenjoy is right--overdrive books as long as they are ePub (preferable) or PDF (okay most of the time) are readable on your reader. Overdrive also offers mobipocket books which won't work on the 505's.
Overdrive has a good search engine at
http://search.overdrive.com/ which allows you to locate libraries in your area. In order to download e-books from a library, you'll need a library card. Most libraries list the requirements in order to get one of their cards, and in most (all?) cases they have some sort of residency requirements. I believe there are a few libraries who will offer cards to non-residents for a fee. I know the New York Public Library used to do this for $100/year. (I have one that will be expiring soon.) But they have recently stopped offering these.
Good luck!
dordale
