I've seen these in at least two museums (Computer History Museum in Mountain View, CA and the Smithsonian Air & Space Museum in DC). They definitely make for good museum pieces, and you could probably pull enough parts together to get at least one working if you really wanted to pull this off.
Incidentally, a Cray-1 uses 115 kW of power when running. Would that be a new power consumption record for a device that's just running Doom?