In reply to Clarence:
I got something from Cowon a while ago that seems pretty good. Mostly specific portable music devices seem to be aimed at hi-def sound these days, and mega expensive, but there are (or were) still a couple of options in Cowons range. Mine does music, radio and video playing (so can, I think, display artwork) and seems to have a pretty good battery life - 40-50 hours of listening, perhaps.
Can't remember the specific model name, though