In that case, consider the B&M Luxos U headlight. The U stands for USB. It will power/charge USB devices as you ride. It's suitable for phones, GPS units, and the like--low-power devices. Has a nice daytime running light mode as well. It's not a bad headlight either. However above 17-18 mph or so, I feel like I'm overrunning it.

My other bike has the original Schmidt Edelux light (as opposed to the updated Edelux or the new Edelux II). That light's good for up to 25 mph. Real nice "throw", but it's a fairly narrow beam and pretty dim up close to the bike. The newer versions are supposed to light the near-field better than mine.

One thing about the Edelux is that it has an ambient light sensor to turn it on and off. I mention this because when it does, I cannot tell by pedaling effort or feel. In broad daylight it will switch on under bridges and off again coming out. The only way I know it does this is from the reflection on the fender.

Yes, some of my effort goes into making electricity. No, I can't discern a difference in the bike--or more importantly, in my quads--when the light switches on. It doesn't suddenly become easier when the light switches off either.

Finally, yes, dynamo systems are the most expensive way to make light. (In the USA anyway. Acidfast will chime in here shortly telling us they're really cheap in Europe.) There are also battery systems that are considerably brighter and cheaper at the same time. Only you can decide for yourself whether or not the convenience and security are worth it to you. I decided to equip both my commuters with them. Took me four years between the first and second one, but I'm happy with them both now.