There are a lot of interesting songs on the 20 years of Jethro Tull box set. I think John didn't review it? In my opinion, late 80's Jethro Tull is a lot more pleasant when you condense it to one song like 'Part of the Machine'.

They have lots of good rarities actually, I think my only similar experience has been the various Bob Dylan bootlegs and compilations of unknown early work.