As a fan of LEGOs, any way to combine computers and LEGOs intrigues me to no end. Recently a couple enthusiasts of everything computer-related teamed up to build a Turing Machine, which is basically a machine that simulates computer processing, out of a LEGO Mindstorms kit. The main purpose of a Turing Machine is to show a simpler model of how a modern-day computer works. The LEGO machine in the video below was made to honor Alan Turing, who came up with the idea of the original (non-LEGO) machine.
Read more on it here.