Sony's Clie PEG-VZ90 is a palm-OS powered PDA that has a 3.8" 480x320 AMOLED display. In fact it's the first PDA with an OLED display.

OLED type: 

3.8" 480x320 AMOLED

Tags:
Kyulux - Hyperfluoresence OLED emittersKyulux - Hyperfluoresence OLED emitters