Grafx2 is a bitmap paint program that allows you to draw in more than 60 video resolutions (from 320×200 to 1024×768, including most of the standard Amiga resolutions : 320×256, 320×512, 640×256, 640×512, etc…).

http://code.google.com/p/grafx2/downloads/list?can=2&q=label%3AOpSys-gp2x