I recently bought one of these and couldn't be happier.
They're still on sale for 50% off ($10 USD) and work very well because it has a lever to make good suction. I mount mine upside down from the picture so it sticks out a bit further into the car. With it being a bit longer than the original mount, I can mount my TT just the the right of my rear view mirror. Since the end of the mount swivels, I can aim it to the driver. Mounting up high does two things...
1. The roof of my car provides shade for the dispay.
2. It's high enough that you can't see the mount from outside of the car because of the window tinting up high on the windshield.
Here's a link:
TomTom Windshield Pedestal Mount with Swivel-head Tightening Nut:
http://www.semsons.com/miwipewiswti1.html