RXS:Redshift sounds like a racing game, but in actual fact it's a company who make hands-free car kits, and they've made the rather genius "Bluetooth Rear-View Mirror Hands-Free Car Kit" pictured above, that does exactly what it says on the tin. It clips onto your rear-view mirror, and there's absolutely no wiring required.
It has some quite nifty features, too. The mic and speaker are integrated into the plastic, and the caller ID gets displayed on the mirror so that you don't have to take your eyes off the road to see who's calling. It also comes with a bluetooth headset that you can use if you're still on the phone when you leave the car.