Recently, there was (one of many) awesome posts over at Cheesycam, where Emm talked about accent lighting created from running lights that go under cars and cheap, wireless $15 LED strips with an adhesive backing. He mentions Steve Taylor's video that puts these lights inside a clamp light reflector for maximum effect.
When I got my set, I had a hard time getting the LED strip to stay inside of my reflector, possibly due to the smaller size. Instead, I wrapped them around a 3/4" PVC pipe where they held firm and were compatible with my PVC light stands (if you want to put them on a regular light stand try this). I like the various lighting effects that could be produced with these, though their use may be limited by the limited remote and strobing issue seen in the video.
If you want to use them in the field, there is the option of powering them from the inexpensive 12v batteries that I use on my external SD monitor. The connectors are the same as the provided power supply, making this an easy (and cheap) purchase.