The Surefire M952V-TN led light. Longer run times than the incan varsion, and if you happen to have night vision equipment, you can use the IR setting.
I also like the M93 mounts on the 952 over using thumb wheels on the 951 for attachment.
I'm currently using an Armytek Predator on my custom built AR-15. very nice light for this application. Very good throw for hunting application with a green/red filter, and with a difuser, will light up a room very well for home defense.