Ethan Winer plays all 37 separate parts on A Cello Rondo, including the percussion, on his cello. He also composed the song. The music is about 6 minutes long and the end of the video shows his digital music editing and some of his film setup. Not only is the production quite smooth, showcasing the power of modern technology to allow a single person to (relatively) easily create complex and intricate music, the song is a really good pop tune.
And I thought it was impressive when Dave Grohl recorded the first Foo Fighters record all by himself.
A Cello Rondo at Ethan Winer’s homepage. Multiple links to sites hosting the video as well as a free mp3 download of the song. There’s also as much background information on the project as you could want and some downloadable sheet music if you want to give it your own try.