My problem is that anything important enough to try to do while driving demands more attention than I can give it while I'm in the car. Heck, even when parked I tend to keep the phone calls short (and I use a Bluetooth speakerphone with voice dial) because I'm just not comfortable chatting with disembodied voices while sealed into a metal box. Pretty much everybody who calls me knows by now that they need to plan what they're going to say before they dial, because I will hang up on them if they start dragging out the conversation while I'm driving. (What's up with people calling and not having a clue what they need to say, anyway? I get a lot of calls at work that start out with, "Uh...hi...uh...this is _____ with _____...um...I was...um...")