Franxis and contributors just relesed an updated version of MAME GP2x, which is a port of the famous arcade machine emulator MAME to the GP2x.

Changes:

Slaanesh:
– Added Knuckle Joe (kncljoe) (from MAME 0.37b12).
– Updated Warp Warp. Now playable with full sound.
– Bug fix to Sega Ninja (and clones) in Sega System 8 driver. Background was not correct.
– Added improved MSM5205 ADPCM sound system. This is currently separated to the old MSM5205 core.
Only Knuckle Joe uses this but there is potential to update many other games to the improved MSM5205 (e.g. Rygar).
– Added FRAC definitions (useful for adding MAME 0.36+ drivers).

Franxis:
– Due to the fact the GP2X TV-Out PAL runs at 50 Hz, the video rate is now limited to 50 Hz when using the TV-Out PAL mode,
to improve the video output and to avoid slowdowns using the VSync option.
– Anyway my recommendation to play with TV-Out is: NTSC mode, high overclocking, VSync+DblBuff and frameskip=0.

http://www.talfi.net/gp32_franxis/