Nearly every car has an ashtray, but for non-smokers, it just turns into a small hole that collects dust, trash, and other nonsense. Instructables user hells-oui shows us how to turn it into a smartphone dock.
All you really need for this project is a bit of scrap plastic, an old dock connector for your phone, and a few tools. The how-to uses an ashtray with a lid, but if your ashtray is open you could probably mod yourself a lid with a bit more of that scrap plastic. when you're done, you'll have the perfect spot to put your phone, no messy cables required. Hit the link for the full how-to.
Ashtray iPhone/iPod Dock [Instructables]