Ok so there's this band that I sorta like despite the fact that it sounds like one big inside joke and that it only came out with one album, and that I can only really listen to 3 or 4 songs without cringing. It's called Major Organ and the Adding Machine and it's an early collaboration of Elephant Six members, but the names of the members have never been released. However, you can hear Jeff Mangum, Kevin Barnes, and Julian Koster's voice on the album. And, I found on the elf power website, in a listing of their shows, a concert that they had with Major Organ--the members present were listed:

Jill Carnes, Julian Koster, Jeff Mangum, Corin Tucker.

Also elephant 6 related:

I really, really want to see this movie (there's more information on it here). It's all made by people in bands I really like--it's probably very weird.