Here's a video showing off Ikan's Gearless follow focus. These types of systems should work well if you're not pulling long focus, and also if you're using some quality lenses with an easy focus ring. The nice feature about this Follow Focus is the ability to mount it using a 1/4 thread. The Power Arm that they are showing looks like it has a bit of flex to it, but i'm sure there's plenty other ways to mount it solid. Not too shabby, and pricing i'll let you be the judge.
Here's the F3 available over at B&H: Ikan F3 Friction Follow Focus