I'm a sucker for these multiple-track music videos. This guy is Nick McKaig, and he's extremely good at reproducing songs using just his voice. Here's the proof: the Simpsons' theme sung a capella.
It's sounds so good and wacky that I like it better than the original.
According to Nick, he "had to write out the entire orchestration from a recording and perform every part, which ended up being over 30! The violin runs were the most fun to record." So good! [Thanks Karl!]