With free firmware called Rockbox you can make the player much, much more advanced.
What I have so far:
15 gig MP3 player and storage
Recording from Digital source, Line-In or built in mic., 192bit quality at 48khz maximum.
Built in games: Tetris, worms, snake, star, othello and sokoban.
Chip-8 emulator and rom reader:
and alot more!