My old pal Mash has redone his website, and has a brand new set of mods. Most notably, he has this chip for your DS which will allow you to remap your L and R buttons to X and Y when playing GBA games - on the fly. You toggle between the two by pressing L and R together, continuing the long tradition of hackers fixing things Nintendo should have done themselves.

Other nifty mods include an internal rumble pack for the GP32, and - perhaps most impressively, a touch screen for the Game Boy Color. It has three layers - LCD screen - front light - then touch screen. He's definitely got it working, though I'm not totally clear on how it's implemented in-game. The full writeup is coming soon, so watch for it!