Need to up your Google-fu.
- Virtual Console custom injections with NSUI
- GameYoB 3DS
- mGBA
- TWiLight Menu++ (with GameYoB DS included)
And I"d like to add, mGBA is freakin' *excellent* for GB/GBC. It supports tilt games via gyroscope, Game Boy Camera, Super Game Boy borders... it's great.

