Since getting my Kindle, I have always been curious about the device's ability to use library books. Thanks to MobileRead I have been able to rectify that problem. My problem now if finding a decent ebook library that I can check out books. I live in Delaware and this state is so behind in terms of ebooks. They have a very small collection and mostly they are audiobooks. If you live somewhere that has an extensive ebook catalog consider yourself extremely fortunate.
I was able to get a temp ID from D.C. which has a great online catalog. Was able to successfully add a library book using a few tools found here and after 21 days - poof the book was gone which is exactly how I expected it to work. Because I wasn't a D.C. resident the card was only good for 30 days (didn't have the chance to get to D.C.). So my access was removed. I am finding that a lot of states will allow for out of state access to their libraries for a nominal fee.
I went to the Overdrive site and found a library that is closest to my house in Maryland. Called them and they do offer out of state cards for $15/year which in my opinion is worth the $$$. Their catalog isn't great but there is a lot there I have not read and I look forward to using this service.