Jose Gonzalez and Nina Nastasia do.
Wikipedia describes The Books as a mix of acoustic, folk, electronic and aleatoric.
Aleatoric music (from the Latin word alea, meaning "dice") is music in which some element of the composition is left to chance, and/or some primary element of a composed work's realization is left to the determination of its performer. The term is most often associated with procedures in which the chance element involves a relatively limited number of possibilities. --Wiki
"Smells Like Content" from Lost and Safe
(watch it in full size, it's amazing!)
"Twelve Fold Chain" (live) from Lost and Safe
"Take Time" from The Lemon of Pink
I love and recommend 2005's "Lost and Safe" and 2003's "The Lemon of Pink," both on TomLab Records. They self-released an EP in 2006 and a DVD of videos in 2007. I'm looking forward to a new album from them soon. *fingers crossed*