Apparently this guy is pretty big in the internet gaming world, but I just found out about him today. This guy does acapella renditions of various video game musical scores. I was listening to his stuff all day at work to help me concentrate, although part of it is that you should watch the videos, as he does numerous parts at once, recording them all at different times, and then playing them back at the same time. Here's a playlist of his most popular uploads. His name is Smooth McGroove.
http://www.youtube.com/watch?v=4qwKCQ4M2Nw&list=TLat5yrpwb5mPfjH_jTe5v-85FO5Jj0oVB
http://www.youtube.com/watch?v=4qwKCQ4M2Nw&list=TLat5yrpwb5mPfjH_jTe5v-85FO5Jj0oVB
