A team of computer scientists at the University of Southampton in the UK created a supercomputer out of 64 Raspberry Pi matchbox Linux-on-a-chip computers and Lego. The team included six year old James Cox, the son of project lead Professor Simon Cox, "who provided specialist support on Lego and system testing."
Here's a PDF with instructions for making your own Raspberry Pi/Lego supercomputer.
Professor Cox comments: "As soon as we were able to source sufficient Raspberry Pi computers we wanted to see if it was possible to link them together into a supercomputer. We installed and built all of the necessary software on the Pi starting from a standard Debian Wheezy system image and we have published a guide so you can build your own supercomputer."
The racking was built using Lego with a design developed by Simon and James, who has also been testing the Raspberry Pi by programming it using free computer programming software Python and Scratch over the summer. The machine, named "Iridis-Pi" after the University's Iridis supercomputer, runs off a single 13 Amp mains socket and uses MPI (Message Passing Interface) to communicate between nodes using Ethernet. The whole system cost under £2,500 (excluding switches) and has a total of 64 processors and 1Tb of memory (16Gb SD cards for each Raspberry Pi). Professor Cox uses the free plug-in 'Python Tools for Visual Studio' to develop code for the Raspberry Pi.
Professor Cox adds: "The first test we ran – well obviously we calculated Pi on the Raspberry Pi using MPI, which is a well-known first test for any new supercomputer."
(Images: Simon J Cox 2012)