I maybe a bit late to the party here but if you haven't heard of this guy he does some pretty impressive Acapella renditions of classic video game tunes.
Here is him doing Storm Eagle's stage theme from Mega Man X
Mega Man X - Storm Eagle Acapella (http://www.youtube.com/watch?v=W54gF6QxeqM#ws)
and here is him doing Stage one of Contra
https://www.youtube.com/watch?v=l2yYauKujfM (http://www.youtube.com/watch?v=l2yYauKujfM#ws)
and here is a epic rendition of Guile's stage theme from Street Fighter 2
Street Fighter 2 - Guile Theme Acapella (http://www.youtube.com/watch?v=4qwKCQ4M2Nw#ws)