Jethro Tull of course! Listen to "Thick As a Brick", which is a one "song" album. If you've never heard them before, I reccomend checking out the live version from Madison Square Garden on youtube, just get an idea of what kind of person Ian Anderson is.
A little less known great band: Van der Graaf Generator
YouTube - Darkness (11/11) - Van der Graaf Generator
And a little Polish accent in this thread: SBB
YouTube - SBB - Moja ziemio wysniona - Wish (live in Warszawa, 1979)