I've seen Leafcutter John play live twice. The first time was amazing. It was a perfect performance combining the sounds of the guitar, cello and vocals with funny sounds, like from blowing on a straw in a glass of water, live processed with his handwritten software.
The second time was not good at all. He sung loud and uncontrolled like a drunkard, and the whole performance totally missed the nuance and intimicy of the first one. While this left a bad taste in my mouth I have to say I still like his music, and his way of melting together instruments and everyday sounds.
Now you can remix Leafcutter John. There's a competition ending at the end of this month, so you have about two weeks left. There already is a good amount of remixes to be heard on his website, including a very nice one by Sunken Foal. Click on the image for details.