Being in Kansas, you should have access to the Kansas Overdrive site. You can checkout both audio books and ebooks to your Nook. It may require a free Kansas Library Card, that you should be able to get at your local library. you can find out more about card at: <http://www.kslc.org>, and the overdrive site is: <http://kansas.lib.overdrive.com>.
Hope you have/had a good trip!