I picked the Audiobooks app for this Thing. Very interesting idea. I am not one for audiobooks, but I might be now after it is so easy to use on your phone. Even has a "Netflix" feature, as if you exit the program and want to come back to it later it will pick up right where you left off. No having to write down whatever minutes and seconds you were at for later. Streaming is how it is done for the free version, but if you want to download them you can pay for a little better version of the app. I had no problems with my streaming connection, but this could vary depending if you are in a remote area or not.
This is another problem the bookmobile faces. 99% of our stops we have good, quality connections to a 3G signal. For those few we don't we would need a work around to be able to run any sort of circulation program.
The Free Books app I just looked at very briefly. This would be great to show patrons on the bookmobile some of the "classics" that are available to view. From time to time we do get patrons asking if we have a classic section, but due to the small size of the truck we typically only carry books published in the last few years. While it is sad that we aren't able to carry more things, we primarily circulate newer and popular items. You must know your clientele.