Just came across this cool new system for mounting a phone or GPS to your dash. It's called Steelie - you can see it here:
Steelie.
For a decent discount on their stuff, you can go to Kickstarter (a start-up funding site), and hope they get enough backers in the next month or so.
Steelie at Kickstarter. (BTW: Kickstarter pledges are backed by Amazon.com.)
The only downside I see to the Steelie system is that you have to stick the mount to the back of your phone/GPS. For a GPS, that probably doesn't matter, but for a phone, it may make it tough to fit the phone in a belt holster, etc.