I was about to mention those (he said three hours later), I worked at BB corporate up until a couple of years ago and Circuit City et al. were completely off the map. They're sweating over exactly the retailers that you mentioned, especially Wallmart.

Once upon a time, a guy I worked with created an Excel workbook where the user would paste in a ginormous list of parts and it would go through about five minutes of gymnastics to parse it out into a bunch of shipping lists. After he left, guess who got to attempt to fix it when it (inevitably) broke?

So many VLookups...

I own a Sansa, and most of what was posted here applies. I'd add that the shuffle is a real, playlist based shuffle, rather than the random play that my Sansa firmware uses. I don't know which type iPods use.

To clarify the difference:
Shuffle: Create a playlist, shuffle it, then play the shuffled playlist.
Random: Play a song, then randomly play another song with a chance, however small, of playing the same song again or within a few songs.