There's a post-rock/prog-rock band of the Tortoise-ilk called Questions in Dialect, or QiD. They're pretty darned good. Here's a tease for you all. On their website, click "Information" and at the bottom you can stream two songs, "Paper Tigers" and "Walking on Water." Great stuff. They're friends of mine, so I have read a lot of the reviews. They get compared frequently to Tortoise, Unwed Sailor, Early Day Miners, Sigur Ros, and Ester Drang. They opened for Unwed Sailor, in fact.
Questions in Dialect
To quote one reviewer, "If asked to compare Questions in Dialect to other bands, I would probably say that their sound rests somewhere between Sigur Ros and Unwed Sailor, but honestly they sound a good bit different than either of those bands."
Another: "Questions in Dialect is essentially a musical experience that rests somewhere between Unwed Sailor and Ester Drang. Fans of Sigur Ros should be happy here as well."
etc....
QiD are bass, drums, guitar, guitar, and then throw in violin, cello, and dulcimer, amongst other things....
Reviews of album and live show