I got one of the Sanyo dynamos at a bike swap meet for about $10. I installed it on my wife's bike for her. I want her to have lights even though she doesn't intend to ride this bike at night. It suits the purpose well. We found ourselves riding at sunset time once, so she has used the dynamo once. It creates more drag than a hub dynamo but less than a sidewall dynamo. It was pretty easy to install. If I remember right, it has only one wire coming out of it and uses the frame as ground. I had to run a ground wire from the bottle cage bolt to the headlight.

I hear that the roller can lose traction with the tire when it's wet. The chances of my wife riding on a rainy night are small enough to take that risk. I hear the problem can be mitigated by gluing sandpaper or skateboard paper to the roller, and I might try that only because it's an interesting challenge.
[MENTION=73614]rhm[/MENTION], were you unsuccessful at forcing oil into the bearing(s)?