You should all check out UMass Amherst Doo Wop Shop A Capella Group. They have an awesome mashup of Disney singles.
http://www.youtube.com/watch?v=IOoMztym1LU
Also check out Sam Tsui.
http://www.youtube.com/watch?v=Ldjxw0YGxYA
I'm not sure if you've heard of Darren Criss, but he has some of...