Let's forget for a moment that watercooling a Nintendo Wii console is about as useful as putting racing tires on a Pinto. After seeing what one looks like (a watercooled Wii, not a Pinto), we don't care. The final result is a thing of beauty that makes for a great conversation piece, even if it won't make Super Mario Galaxy load any faster.
Bit-Tech.net forum member "Angel OD" posted a multi-post worklog of how he got from point A (a stock Wii console) to point B (a tricked out Wii with watercooling), so if you have the time, money, and nerve, you can try to make your own. It took a lot of modding and machine work, but as far as water cooled consoles go, we have to give the nod to Angel OD for putting together one of the 'coolest' that we've ever seen.
You can follow the worklog here, or jump straight to pics of the finished mod here and here.