I prefer something with a removable battery like an Archo's media player. I've got two.
I can use the newer model to off-load photos from the digital camera and free up its memory, plug in their bullet camera (i.e. a helmet camera) and record movies on the bike, watch movies while held up in a tent, and/or play a ton of mp3 files - all in one device.
If you have a Dish Network receiver, you can plug the Archos into the receiver's USB port and record the movie directly to the unit in a compressed format. You can also play a movie off the unit onto a big screen TV.
Might cost you a bit more than an iPod, but they do a whole lot more as well. For the price of one iPod battery replacement, you could own the Archos. They are cheaper to buy through Dish Network too. Neither has ever skipped on the bike although both are hard-drive units.
Once the Zumo GPS came along, I moved most all of my mp3's over to a 4 Gig Transcend SD card into the Zumo and leave the Archo's for movies and photo backups.