Berkeley has a bunch of
free podcasts on their site from actual classes, some of which may help with CLEP and DANTES tests that you might be taking. For instance, I'm downloading the Statistics podcasts to be able to listen in the car.
You don't necessarily need an ipod or other MP3 player to make use of these though. Technically, you could download the MP3 files with the podcast and just listen on your computer or burn CDs for the car.
More info on podcasts
here.