cell phones
I finally gave in and got one 3 years ago. It really helps with making connections with people while I'm out and about. A lot of the features are useful- camera, 'notepad,' alarm, calendar for appointments.
The problem comes when people use their phones in ways that are obnoxious, inconsiderate, foolish, and excessive. If I don't want to be disturbed I can turn it off or just not answer.