Today I walked past a classroom and noticed an MP3 player left on the piano at the front of the room. For some reason it reminded me of an abandoned pen. We're used to seeing pens lying around, but there was a time when they were expensive and highly prized.
I'm fairly sure you can produce a reasonably featured MP3 player for less than $20. How long before they're like pens--everywhere, given away, easily abandoned, even disposable? They're probably cheap enough now to be given away as schwag at conferences. If you're considering that, you might want to also consider contracting with IT Conversations to pre-load them with great content.