I have an Ipod shuffle, and mostly what I listen to is Podcasts! There are a ton of them about biking, and triathlon, and endurance sports, and anything else you can think of, in lengths ranging from 10 minutes to an hour. Sometimes on a really long ride I will get through all the Podcasts and then I have a bunch of music on there, too. To get them, you just go to ITunes, to the Podcast section, and do a search or browse. They're free. Then, if you like one, you subscribe to it, and it gets automatically updated- new shows are downloaded as they become available.

I ride with only the left earbud, and only on trails.

Nanci