I use mine for listening to music, books, and podcasts!
Oh, and beyond that: Mobile harddrive. I've got Synk (backup, synchronization program) installed on my laptop (home) and iMac (work). This let's me keep up-to-date copies of files I'm working on at both places, and have a handy backup. Upshot is I no longer have to bring my laptop into work and/or muck around with flash drives that aren't quite big enough to hold my files.