The Surefire Titan T1A is the light that pushed me over the edge to become a Surefire dealer, so it was the first thing I put on my opening order from them. The light has probably the coolest interface I have seen, a rotary switch that makes the light brighter as you turn it further. This sounds simple and the concept has been around in home lighting and other applications for decades, but Surefire is one of the first flashlight companies to incorporate it into a handheld flashlight. Since the light does not have a traditional switch to take up extra room, the T1A is also a compact little bugger.
Check out the video below to see what the Titan can do: