I used to talk on the phone while driving... quite often, actually, although not for very long for any given conversation. I've stopped entirely, for two reasons: in the last couple of years, more and more jurisdictions have made cell phone use illegal while driving; and when I broke down and got a smartphone and started receiving work e-mails, I had to have an "unlock" password that makes the phone a giant pain to dial with.
I've done a few regrettable things while driving to/from fieldwork. For example, eating a slice of cheescake. With a fork. In rush-hour traffic.
My worst example of distracted driving was when I was running late for a new field project. I was in a complete tizzy because I was following directions from a mapquest printout, and I was pretty sure I had made a wrong turn. Once I figured out I was indeed going to be more than 10 minutes late (remember, I hate being late), I tried to call the client contact. Oops, that was in a pile of papers tucked in the very deep center console of the cargo van. So there I was, trying to reach way below the dashboard for a bunch of buried papers, then shuffle through them, then dial the number and have a semi-intelligent conversation, all while bombing down the highway.
This is why I have a portable GPS to take with me for fieldwork. It's also why I leave with plenty of time and if I am running late, I find a safe place to stop well short of the actual arrival time.