For years, the champion dark photographers would combine massive halogen spotlights with long exposures and lightpainting to get amazing shots. In recent times, LEDs have stepped up to the plate to provide high output in smaller packages, with longer battery life. However, it will be some time yet before anything but a custom LED package will match a high-power incandescent light. While a sufficiently-motivated photographer can begin stringing batteries and high-power LEDs together, the cost per photon is much higher than with incandescent lights. Considering that I own about 8 LED exploring lights and carry 2 daily, I've gotten my feet wet by buying a pair of high-power spotlights.
Black & Decker V-2 million spotlight,
CPF review, and my pictures:
1 second at F/5, iso 80
3 seconds at f/5, iso 80
This light has a 12v battery and a 35/55watt car headlamp bulb. It gives wonderful sun-colored light, but it visibly dims over the course of 15 minutes running. After a rest, it'll recover some brightness (like any SLA battery). It's bright, costs about $30 (I used a gift card I got for a project), and is reasonably hackable.
Now my other light, the
Stanley HID. My camera broke just before I got it, so I can't do effective comparison shots. It shoots a bar of blue-white light and punches buildings a half mile away with impressive brightness. Pictures coming soon, it seems to stay on for about 20 straight minutes, although starting up is hard on the battery.
Another 12v SLA battery, running an HID lamp (the annoying blue/white car headlamps are bad examples of these). In theory you can change the color temperature by swapping bulbs, I'd suggest it for prettier photos. I'm looking forward to backlit photos with this thing.