LED lights are the future, and they're becoming particularly prevalent in video and photo production. They're light, bright, cool to the touch, and they're coming down in price very quickly.
The LED98a from Fotodiox is a low-cost portable LED light designed for use on-camera or any other situation where you need a lot of light from a small battery-powered package. Included in the box is an adjustable hot-shoe mount, a battery charger, a standard NP-style battery, and two magnetically attached diffusers for both daylight or tungsten color temperatures.
If you're doing any sort of video or photo work, a flexible and incredibly portable light like this can prove to be more useful than you might imagine, and it takes up next to no space in your bag. The amount of light this thing throws is truly amazing.