When I was a kid, I had dynamo powered lights on my bike. They worked great as long as you were moving along, but quickly dimmed if you slowed down or stopped. Now a California company called High Tide Associates has updated this technology for the 21st century with the RollerGen, a bike mounted generator that charges your portable electronics.
Rather than the wimpy 3-5 watts of my old dynamo, the RollerGen can spit out a whopping 30 watts, which get stored in a small battery called the BOS (bar of soap). This sits next to the generator in a small rack over the rear wheel, and there's enough extra room for your electronic gizmos.
This all sounds great, but I wonder how the RollerGen works in the rain. Also, at $495 for the complete system, it seems pretty darned expensive compared to the alternatives.