I would recommend an iPod. I have had an iPod Nano for over a year now and I couldn't be happier. Of course you would want one of the standard iPods for the 30 to 80GB capacity. It has a intuitive user interface, slick design, and syncs beautifully through iTunes. They have great battery life, around 20 hours if you are just listening to music. I'm sure it doesn't last long if you are watching video. Apple has been doing this for many years, so I think it is hardware you can trust (If not you get a 1 year warranty, or you can pay a little more for a 2 year warranty). In my opinion, non-replaceable batteries are not a drawback. I think most companies are leaning in this direction because of the problem of after-market batteries. People will stupidly put incompatible batteries in their devices and that's when things explode. So for consumer safety, I'm fine with non-replaceable batteries. Plus, every year with the technology getting better, the overall battery life gets better as well. In another 2 or 3 years when my Nano battery can't hold a charge anymore, I'll be ready for something newer and cooler anyway. No problem for me. Even if the battery dies for me, I can still use it in my car, since I have a FM radio transmitter that powers my iPod while I'm driving. So worse-case, this becomes my car iPod. :) I am interested to hear what other types of portable media players people use.

How about something completely different? The Nokia N800! This thing looks amazing. Leonard just bought one. It has 2 SD slots that support up to 8 gig each. So it could be a 16 gig mp3 player with no moving parts, great sound (folks say) from the speakers or use your headphones. Besides that, it runs Linux and is a cool wireless tablet computer. With 16 gig of memory it should still cost less than $500.

Hate to be boring, but I have an old 60 GB iPod (gen 4, before video). It's held up great on a LOT of flights, travel, abuse, podcast use, et cetera. I've had it for over two years, maybe three, and it still gets great battery life. For the last year I've listened to it nearly every day in my office, docked in a stereo.