A lot of the pet peeves listed here are mine too, but I will tell about two specific incidences that highlight my two biggest cell phone pet peeves.
In the spring of 1996 I was at my daughter's high school choir banquet. It was very nice--dinner, awards, special recognition for senior choir members. One dad kept getting up from the table during the dinner and the awards part afterward and paced back and forth talking on his cell phone. He might as well have stayed home because he totally ignored his daughter at a very important moment of her life.
Another incident happened a few months ago. I had to go in for a sonogram. I was lying on the table half exposed (let's just say it was the "bikini top" area, lol) when the technician's phone rang. She stood there over me taking a personal phone call (it sounded like it must have been her son) for 3 or 4 minutes. When she was finished she never said so much as "Sorry about that." She just went back to doing the sonogram.
My biggest pet peeve is people putting others in danger (driving, etc.) but these two were biggies for me.