I made a cover of the Final Boss Theme from Mega Man 4, as well as a 16-bit version of said song, in FruityLoops Studio 9 and some NES VSTs. I figure I shouldn't submit them seeing as we usually go for 'real' techno or rock or any genre using modern instruments, but they're here:
Mega Man X remix:
Looping version (a bit loud):
I tried to make the 8-bit version a remake as close as possible to the original, as opposed to a ReMix, so that's just another reason to not actually submit it here. However, I'm extremely proud of it. It's my greatest personal achievement in music, and I'm glad I managed to do it.