Thanks to Ramblinprose for the pic.
Weapon lights are an outstanding piece of kit to have for your firearm. With many modern pistols being produced with rail systems and advances in flashlight technology bringing costs as well as size and weight down, those tacticool toys that we drool over are no longer reserved for just the rich and elite units. A few of my choices would be those offered by Streamlight and Crimson Trace. I do not personally recommend the above picture as a reliable method, unless of course you are Uncle Fester.