Here is what I used for my "redneck windscreen iTouch mount":
BLACK ROTATING BELT CLIP HOLSTER CASE APPLE IPOD TOUCH 4:
BLACK ROTATING BELT CLIP HOLSTER CASE APPLE IPOD TOUCH 4 ACCESSORY | eBay
Car Suction Mount Cradle Holder for GARMIN NUVI 265:
Car Suction Mount Cradle Holder for GARMIN NUVI 265 265T 265WT 270 275 275T 465T | eBay
From the clip holster we only need the part which holds the iTouch (duh), so take of the belt clip off and you're left with the cradle, you might need to dremel off a piece of plastic which sticks out from the back.
Now we have to create something which allows us to mount it to the windscreen.
Now dremel off the protruding parts on the side of the Garmin Nuvi holder and you're left with a baseplate which is attached to the suction mount.
Now hot glue your two parts together, make sure that the suction mount is not in the line of sight of the camera (in the picture you'll see that the suction mount is not centered, which is not a problem as the ball of the suction mount sits very tight). I also attached two strips of velcro (only the felt part) to stop the iTouch from wiggling in the cradle
The final product looks like this:
