The Newsmy XO is a the thinnest MP3 player (only 5mm). It also doubles as a mirror, with a special glossy finish.

Newsmy XONewsmy XO

It plays AVI files and has an FM tuner. It will retail for 44$ for the 2GB version in China.

OLED type: 
1.5" full-color OLED
Kyulux - Hyperfluoresence OLED emittersKyulux - Hyperfluoresence OLED emitters