NASA Dryden Flight Research Center has a gallery of digitized video clips of some experimental and/or historically significant aircraft.
Possibly more unique than the SR-71 (that would be the Blackbird) or Mars Rover is the video of a Controlled Impact Demonstration (pictured right) wherein a Boeing 720 was intentionally crashed in order to record the results.
Is harrowing the right word?
(originally via BoingBoing, w/ some additional sniffing around to find the details)