By now you should be well aware of the cellphone usage laws for your state, but if you can't bear wearing a Bluetooth headset on your ear, there are other options. This takes the traditional Bluetooth headset and turns it into a god-awful ugly neck-mounted contraption is that will draw more blank stares than if you just used a regular Bluetooth headset. It does include one nice feature.
You wear the RoadRunner Bluetooth Communicator around the neck, therefore the microphone can sit directly on your voice box and transmit noise directly from your larynx, which is capable of eliminating almost all ambient noise. It supports nine hours of talk time and includes a rechargeable battery. It's available for $80 or so from Pro-Idee. [RoadRunner Communicator via CrunchGear]