I'm considering getting a small camera. Perhaps the best place to mount it would be on the headtube, where it is basically out of the way of everything. I've got Ultegra 6700 on my bike, so the camera would have a good view. Handle bar mounting would be tricky since I already sometimes have a light and the Garmin mount.

Any idea what mount to use though? Handle bar mounts are too small to accommodate a large diameter CF head tube.

If it's a GoPro, this is probably exactly what you need.

Mounting to the frame rather than the handlebars also means it'll be a lot more stable than it would be if on the handlebars (as it's always pointed where the frame is currently headed, not where the front wheel is pointed this instant), so if you can do that ... you should.

It may catch (in its video) your bars and cables moving around ahead of it, but that's often not a bad thing.

May not totally answer your request, but I've been loving my Mobius Action Cam.
The reason I mention it, is it's quite small and can be mounted a myriad of ways with available mounts and/or a little ingenuity. Is Helmet mounting an option for you?
I use a Cateye Stealth GPS mounted on a bar fly mount, and then mount the camera upside down below the handlebars on my right hand side of bars with a Minoura Japan ? VC-100 which is surprisingly stable.

Two minor complaints on the Mobius - battery life = :80 minutes; and no screen. But if you can live with these two it takes very good quality HD footage and there is a community of passionate RCers and hobbyists actively developing behind it. The whole thing feels very open source to me, unlike things I've seen in the photo camera world where a Mfr might only deliver a couple very minor firmware updates over the lifespan of a camera/device.

Get a few shares of Go Pro Stock, too, when it goes Public.

If you get a bullet shaped cam; Contour, Sony, Virb, etc. I think you'll have an easier time
mounting it to the head tube. I use a ContourGPS and mount it everywhere on my bikes;
seatpost, fork, rear triangle, handlebars, etc. And I don't use any specific mounts; just
strips from an old tube. In this vid, I set up the camera on the top tube. I could have placed
it right by the headtube; but I have a luggage mount in the way:

https://www.youtube.com/watch?v=AopS...IoDLA&index=21

I'd be leery of mounting it to the headtube. The mount has to be fairly tight so as not to bounce around.

I have a "clamp" type camera mount with the 1/4" tripod type connector that screws into the bottom of my Drift HD Ghost camera. I mount it on the handlebars just above the head tube. The camera doesn't seem to affected by any of the roads I've ridden on. Stable mount and stable picture, even on surfaces that aren't really smooth. I've tethered both the mount and the camera to the handle bar "just in case". The type of camera clamp mount would lend itself to other mounting locations if I chose.