Couldn't decide whether to post this in here or the music section (applies to both). Anyways, its this acapella group called the Button Mashers and they do various covers of popular video game tunes. I thought this would be real shitty, but they are actually quite good and enjoyable.

Mario 2, and Dark World from ALTTP sound great, as well as the chrono trigger tunes, enjoy.

http://olremix.org/remixers/The_Button_Mashers