I got a gp2x for christmas and after playing with some of the emulators I decided I really wanted to play some games that didn't have emulators out yet. I wanted to play Ninja Golf (Atari 7800) and Hunt the Wumpus (TI 99/4A).
So a few weeks ago I started porting xmess to the gp2x and it's running pretty well, better than I expected. For those that don't know (I doubt most of you *don't* know what mess is) mess is a multi-system emulator. I have got Atari 7800, Colecovision, and TI 99/4A working on it. I'm currently working on Apple ][ and Coco support. I don't plan on doing Atari 800, C64, etc since there are already dedicated emulators (which are VERY good) available.
It's a lot of work, but very fun and made a little easier by this thing being pretty much a Linux box so I can develop on my Linux workstation and it's pretty much the same for all intents and purposes.
Anyway, just thought folks might be interested if they have a gp2x.