Let's face it, most guys won't ever use a Follow Focus system that requires rails to mount, and lens gears to shift around. There's plenty of people who are already happy with something as simple as a Silicone Jar Opener to help move that lens gear around. Especially for some of those Panasonic lenses that seem to rotate forever. Check out the video from Vimeo member Tony Carretti a while back (below).
There's been plenty of DIY ideas based around a little handle around the lens gear, some that mount on the lens ring using zip tie straps, some methods using pipe clamps and bolts. All very effective methods for the filmmaker on a budget. Now if you like the idea, but are concerned about the aesthetics of your gear (maybe to impress your clients), check out the adjustable focus / zoom lever from Sunwayfoto.
The Focusing lever is precision machined from solid aircraft-grade aluminum with an Anodized finish, solid and durable. To maintain a slim profile, they come in about 4 different sizes from small to large depending on the diameter of the lenses you're trying to mount these to. More information on these things following the link (click here).
Adjustable Focus / Zoom Lever SunwayFoto - via eBay
Also available via Amazon (click here)
Sunwayfoto Focus Lens Zoom Lever Handle - via Amazon