Xbox Linux cluster
Anandtech took eight Xboxes, saddled them with modchips and new BIOSes, and then combined them to form an Xbox Linux cluster to see what kind of distributed computing power it could muster. For a total of $1830 they actually got a decent cluster, but the lack of onboard memory and crippled Pentium III processors on the Xbox held things back, which is probably why everyone would be more impressed if they'd done this back in 2002 rather than today.
[Via Joystiq]