Bjimba has ported DosBox to the GP2x. Release notes:

I looked into various options: porting one of its clones, running it under the already-ported Bochs emulator, rewriting from scratch… I finally had some success by porting DosBox to the GP2X platform. It’s similar to Bochs in that it is a software emulation of the Intel CPU, but it also directly provides the DOS infrastructure, and is designed primarily for DOS games.

Well, it works well enough for me to play BlockOut, so I’m making what I’ve done so far available for download here.It’s definitely for people who like to fiddle, since you really have to rewrite obscure text configuration files for every game you want to play, and you have to creatively map the GP2X buttons to enough keys to make the game playable.