It can be used on variety of electronic parts with Raspberry Pi and other small computers being the obvious choice if you are into overclocking. Water cooling is silent and can take away large amount of excess heat. It goes without saying, if the water leaks out it will badly damage your electronics.
You could also use 3d printed peristaltic pump to push the water or just have it stream from faucet ...
It would be interesting to see how much could the design be enlarged ...
|3d printed cooling block attached to a Raspberry Pi. Copper penny is on the bottom touching the chip ...|
You can find all the instructions and files to make it yourself at:
Here is a video of heat conductivity test: