I would like an e-ink or monochrome old style low power lcd display that is on the whole time the player is now. I hate these colorful displays that need to be off most of the time to conserve power. A digital watch can have its display on constantly for year with a tiny button battery. With an mp3 player, just having the display on while the player is on is enough.
E-ink is an interesting idea, although I’ve never seen it on a truly small screen lik a DAP. I just pulled out my Nook Simple Touch e-reader, which has such a screen…I last charged it fully on the first of this month, and it has been powered on the entire time…and the battery display reads 80% still. It’s been inactive, showing the screen savers, for the last two weeks, as I had finished the book I was reading…but still, 20% battery use in 18 days is not too shabby.