In 1990, the Broad Band X-ray Telescope orbited the Earth aboard the Space Shuttle Columbia, gathering data on galactic and intergalactic X-ray energy sources. Now it just gathers dust as government surplus. Unless, of course, you've got $7 (£4.4) million and a hankering for some nifty NASA memorabilia.
The BBXRT is not the sort of telescope one simply mounts on the back deck, mind you. It weighs 840kg, nearly a tonne, so you'll at least have to mount it on the garage roof or some other such sturdy structure. 84 people have already put offers in but apparently haven't hit the reserve price. [Ebay via Boing Boing]