|Water cooling is mainly for enthusiasts, even though there are attempts to make it more mainstream, such as the LCLC from Asetek, which aims to minimize complexity and cost, the two biggest drawbacks of water cooling. Another problem is that water cooling is not much better than the high-end air coolers we have today, it's better, but the margin is sometimes a bit too thin. Scientists at Georgia Institute of Technology have found a way to improve water cooling by using sound waves.
In terms of liquid cooling, letting the coolant boil when coming in contact with the hot surface will remove energy faster and more efficiently as more energy is needed to convert the liquid to gas. The temperature-energy diagram below explains how there is little energy needed to raise the temperature, but turning the liquid into gas requires a lot more.
The downside of turning the liquid into gas is that it can easily form a film that prevents the water from coming in contact with the hot cancer. The air bubbles will simply stay at the surface and block the water. In previous experiments they've used water jets to rid the surface of the film, but the equipment needed was bulky and poorly suited for commercial use. Instead they placed an acoustic driver (speaker) that sends out small amounts of sound waves at 1KHz. This was enough to remove the air bubbles from the hot surface and improve cooling efficiency. They saw an improvement of 147% when the driver was just a few millimeters away from the heat source.
Commercial applications are sadly far away, but it sure sounds like a possible application.