I have an HTC Evo and I am in love with the Audible for Android Application. Again being an accoutant I love statistics. This app shows you the number of hours that you have listened, has badges that you can obtain as well as tracks the size of your library. I always have my phone with me so I can listen whenever I have a few free minutes.
Also quick FYI for audiobook lovers who have an iPhone, Audible also has an iPhone app as well.
I also love the 1.5x narration speed option — not available on the iPod player app on iPhone. 2x is way too fast.