By far, the things that drive me the craziest come from people:

People who don't put their cell phones on vibrate when in public.
Corollary: The need for those same people to have obnoxious ring tones.

Narrow WalMart aisles and the wide people who fill them, oblivious to those behind them.

People who keep talking despite your not-so-polite hints for them to shut up.

People who stand too close to you when they talk.

Motorists who lay on the horn because they are too lazy to walk the 30 steps to knock on the door of the person they are picking up.

Work-out partners who don't wash their doboks.

Online trash-talkers. RL trash-talkers piss me off enough, but hiding behind online anonymity to avoid consequences is sophomoric.

Slow-moving motorists who straddle the line.

Commercials that are considerably louder than the television program they are in.

Comb overs. Being bald isn't nearly as bad as being bald but trying to hide it.

Non-educators deciding what and how schools should teach. You don't hire a carpenter to wire your furnace or plumb your house.

The person who created automated telemarketers. Dial zero to talk to a real person, then let them know what you think.