my first beowolf cluster, I built because I wanted to improve my pentium 486's chances at doing well in some random FOSS benchmark (PiMark? it calculated pi.... and you could 'donate' cpu runtime to help calculate more digits of pi.) It was cobbled out of my dad's spare part's rack.
Should have seen my dad's face when he realied why i built the beowolf.... "You mean... you did this. FOR PI??"("Okay, that's actually cool.")