What fairly high capacity (4 - 8 or more gig) players, preferably flash, are there that are battery operated. I don't mean a rechargeable battery, but by flipping a AAA or so when it dies.

My Zune runs out of juice at the most inopportune times and I have to whip out my trusty old 3 gig Sansa that runs for 15 hours on one AAA cell.