In the process of trying to figure out how to download MP3 books to my Nook from my public library, I ran across this website www.overdrive.com/partners/libraries.asp

They have a list by zip codes of public libraries that are hooked into their Overdrive system that have ebooks/mp3 books, etc (you have to download their free Overdrive software). My understanding is that you can sideload some of these books (although I haven't tried an ebook yet). It looks like now most libraries make anyone in any location of their state eligible for their library cards. Like for LA County library, you now just have to have id showing you live in the State of California, instead of in the County itself as it used to be.

If you can't find a library in your area, I believe I read that out of state patrons can buy an annual membership for $15 to the Philadelphia Public Library and so can then download their ebooks free.

I've only downloaded an MP3 book so far and only as far as to my desktop. I'll try to sideload it later and see how that works.

Maybe this is common knowledge that just wasn't common knowledge to me...sorry if I'm repeating something already well-known in Nook circles!

ETA: Link to Free Library of Philadelphia: libwww.freelibrary.org/register/getcard1.cfm