This is just something so cool we had to show you. If you are not familiar with what Raspberry Pi is, it is a credit-card-sized single-board computer powered by a 700 MHz ARM-based processor. Well James Couzens has decided that he wanted to add some watercooling to this tiny computer. He proceeded to create his own water-cooling system for it, complete with miniature pump and waterblock.
To me this is one of the coolest mods that I have ever seen. It is completely unnecessary as this small computer does not generate any heat really at all. But it shows you what someone can really do if they want to. You can check out the full build log and much more over at the bit-tech forums.