The one that I use for the car is the [ame="http://www.amazon.com/Motorola-Oasis-Bluetooth-Headset-Packaging/dp/B0041D81WQ/ref=sr_1_1?s=wireless&ie=UTF8&qid=1326768786&sr=1-1"]Motorola Oasis[/ame]. It can pair with two phones unlike a lot of other headsets.
I currently use this new NoiseHush N780. Im currently testing it for a local cell phone shop and it sounds, feels and looks great...i can only complain that it uses a "mini" usb connection which most phone no longer use for charging.
+1 for the blue parrott. I used one when I was still an over the road [truck] driver. Excellent sound quality, which is essential when your dispatcher is an idiot.