When I was about 14-years-old, I went on a tour of UCSD's Supercomputing Center, where I was able to briefly step inside a functioning supercomputer, a Cray T90 that took up several rooms, required climate and humidity control, and doubled as a decent place to sit. It was a formative experience for me.
Chris Fenton and Andras Tantos are working to recreate the original Cray 1, by building a custom PC case that recreates its iconic design. Chris documented the build process for the case on his blog, but the really interesting story is the digital archaeology that Chris and Andras have had to do to recreate the Cray OS so that it will run on a FPGA. After some impressive work rebuilding the Cray OS from some ancient hard drives, the next step is to find a working compiler, so they can write new programs that will run on the machine.