If you’re not lucky enough to have a car dock made specifically for your Android-powered phone, check out some of the “generic” alternatives. In this case you’re not going to get a Bluetooth connection or power pass-through, but at least you have your phone placed in a convenient location, and up out of the cup-holder to someplace more useful!
One of my Christmas presents was the Arkon SM514 which fits the T-Mobile G2 (HTC Desire Z) very nicely. It has a full range of motion and locks snugly in place, and holds the phone very well.
It doesn’t have any sort of power pass-through, which would have been nice, but this omission means the dock is “generic” enough to hold a variety of phones. So far I’m impressed.