Really nice lights, I'm trying out a small cabela's brand pocket flashlight, seem's well made and certainly is bright. But my old C celled 'cop light' still is with me in the truck, it has a comforting heft.
Both Mag Industries and Nite Eyze (aftermartket) make LED "bulbs" that replace the regular halogen bulb in the larger MagLites. You get about 1/3 less light (as you do with all LEDs), but gain the benefit of far longer battery life, and near-infiniute bulb life.
The units are packaged like the OEM lightbulb, so they go in just like another bulb. $20 for the Mag brand, and $10 for Nite Eyze. Mag actually makes a couple of models, depending on the number of batteries in your flashlight, while the Nite Eyeze auto-adjusts for voltage, so only one model is needed.
I upgraded my Mag before retiring it. And I can still grab it from the closet if I need it. Of course I'm not a big fan of the dark. That's why I also have a large stash of Cycalume sticks at home, in my truck, and a hidden pocket in my brief case.