When I was at WPPI, I saw Doug Gordon with this cool little light that he uses for his portraits. It's an LED light, with rechargable battery. It's color balanced and also comes with an amber lens cap to create tungsten color balance and a neutral diffuser cap to soften and broaden the light. It looks to be very solidly made and is compact enough to throw in your camera bag for a quick kiss of light anywhere. What's really cool about it is the infinitely variable brightness control that allows you to dial it just right so that it blends nicely with the ambient light - and this is really where it's designed to be used. While you could use it as a main light by itself, it works best - and looks most natural - when you use it to supplement available light (which is why it comes with the tungsten colored cap). You could hold it with one hand just off-camera to create some directional light, or mount it right on the camera to create straight on fill. It comes with a mini hotshoe mount/ball head.
I did a few quick sample shots at home tonight to see how it works to liven up some indoor natural light snaps. For the headshots of Clare, I popped the amber gel over the lens and set my white balance in camera to tungsten. This kept the background and foreground light temperatures the same for a very natural feel. I varied the brightness of the light to find just the right balance of natural/artificial light. Kick it up for a more dramatic feel and dial it down to just add a little kick. As you can see, it makes a dramatic difference in the quality of the images vs. the natural light alone. I can't wait to try it on a live job! My only complaint would be that the diffuser and amber colored caps are a bit tight and difficult to get on and off quickly. These might loosen up with more use, however. Otherwise, it is of very high quality, easy to use, has a long-lasting built-in battery. and is compact. The TorchLight is available from Doug Gordon Equipment
Here's the TorchLight complete kit with the amber cap on it to balance with the existing tungsten light. I dialed the TorchLight down to it's lowest setting. I set my camera to tungsten WB. Notice how neutral the color temp is and how it matches the existing tungsten light (Pen not included :-)