I think about a compressed air+water aerosol injection CPU cooling system.
This technique should make it possible to get 3 cooling effects at the same time:

A) Gas expansion cooling effect. (Refrigeration effect)
B) Windchill effect.
C) Adiabatic effect

http://de.wikipedia.org/wiki/Windchill
http://en.wikipedia.org/wiki/Refrigeration
http://en.wikipedia.org/wiki/Adiabatic_process

With such a system it should be possible to cool Server systems in a energy-efficient way with very low temperatures compared to air or water based systems.
The temperature of such a system should be at 10C independent of load.

I'm thinking about building a prototype.