In Japan, Toyota and Nintendo have teamed up so that you can control a Toyota navigation system with a Nintendo DS.
It requires a Kuruma de DS game card (translatation: Use the DS in the Car). It works over Bluetooth after pairing with a Toyota Smart Navi system.
The Smart Navi system costs the US equivalent of over $2,500 and the Kuruma de DS may be purchased through Toyota for the equivalent of $92. (A DS must be purchased separately).
Photo via 4gamer.net