I've got a Garmin StreetPilot 2720. The 2xxx line comes with a bean-bag style mount that allows you to set the unit on the dash instead of sticking it to something with the suction cup. The bean bag idea sounds strange, but Garmin executed it really well; it's got a nice rubber bottom on it, and it distrubutes weight over a wide enough area that it really does not move when you turn the corner. Such a mount is available as an accessory for just about all Garmin automobile units.

The unit also doesn't have to be that high to work. Once it has acquired satellites, I've found that it works fine down by the cupholders. It's harder to see the map down there, but if you're listening to the voice guidance it's fine.

There's a great thread that was posted a while back about the Nuvi 350, and it includes pics of some other mounting ideas.
http://www.toyota-4runner.org/showth...threadid=15455