Don't laugh but I carry a Mag Light Mini (2AA batteries). The light isn't that powerful but it gets the job done. The Mini Maglight is pretty cheap (under $10) and the AA batteries are a lot cheaper than the lithiums. The run time is also a lot longer. It doesn't have the push button tail cap but the light is focusable. The main reason I carry it is I can use it as a kubaton when I can't carry a gun or a knife! You can't crack a skull with that puppy and you can carry it anywhere (airports, airplane, otherwise sterile environments).
