At this exact moment, we are selling three cooling solutions: air-cooled, water-cooled, and single stage vapor phase change cooled systems.
There are other cooling options in the "overclocking world", such as Peltier-cooling (relatively expensive, holding great promise, but also still too new to be 100% reliable), cascade cooling (complex, noisy, potentially dangerous to underskilled builders, and very large), and "extreme cooling" with Liquid Nitrogen and Liquid Helium.
Two of our engineers, Ed Trice and Bill "Buckey" Harmon, are researching a potential new breakthrough in Liquid Cooling. Currently referred to as Ammonia Subambient Heat Transfer, it makes use of one very important property of NH3: It has a higher Specific Heat Capacity than liquid water. Ammonia can remove about 1.3 to 1.5 BTUs/(pound x degrees Fahrenheit) at temperatures straddling either side of the boiling point of water. Water is, by defintion (at best), 1.0 BTUs/(pound x degrees Fahrenheit). All other things held constant, an NH3 cooling solution can remove 30% to 50% more heat per pound of coolant than could a water based one.