California recently joined a growing number of states that require drivers to use hands-free devices while driving. In other words, if you want to use your cell phone in the car, it better not be pressed against your ear. You've got two options for avoiding tickets: a Bluetooth headset or a Bluetooth speakerphone.
eCost has the Kyocera K323 Bluetooth speakerphone on sale for $15. It's powered by your cigarette lighter and offers voice dialing (if your phone/carrier supports it), last-number redial, and volume-control buttons. How's the sound quality? I have no idea, but in my experience, Bluetooth speakerphones do a terrible job drowning out road noise--bad news for the person at the other end. Of course, my car is a noisy 8-year-old beater, so your mileage (heh) may vary.
What's your preference for hands-free phoning: headset or speakerphone?