It's bad enough to get hit on the head with a MagLite, but here's one that'll burn your house down too.
All right, so it's been slightly modified. How'd they do it? Twelve 1.2V NiMH (rechargable) batteries capable of a sustained 10 amp draw--encased in that sturdy skull-cracking MagLite body--and an Osram HLX 64623,12V bulb "which is being overdriven to 14+V, to about 140 watts, with an estimated light output of about 4000 lumens." A regular 2D MagLite puts out less than 50 lumens, according to Mr. McCracken at extreme-geek.
The reflector is made of metal, as a stock one "would melt almost instantly from the heat of the Osram." The original switch has also been replaced with something meltproof.
Who's the genius would bother building one of these? Mac's Customs. There's some lively discussion on whether it's for real. Here's a site devoted to flashlights.