Dr. Hatio: Hacks of Dr. Mario for the Nes and Game Boy. The point is to kill virii with beanie pills.
Nes and GB v.1.0

Mr. Happyface: A hack of Ms. Pac-Man for the NES.
NES v.0.5

Doki Doki Panic: The "original" US Mario 2.
Not released yet.