I guess the biggest pet peeve I have are people who act as if you're beneath them.  Like nothing you say is ever good enough, or nothing you do is good enough.

I also hate closed-minded people as well.  And, people who have the notion that if you don't think they way they think, you don't have the right to think at all.

Perhaps one of the most annoying pet peeves I have is people trying to force their beliefs onto another person, whether it be political, religious, sexual, or ethical.  I'm my own free thinker, and I believe in being an individual.  I don't like to be forced to change for anybody.

Omega - Mine just says, "Wait for it.... GO! ::beep::"

Cap'n - complete agreement.

I dislike people who lean too heavily on their cellphones. By that, I mean that, when you're hanging out with someone, I feel it's rude for them to walk off to take a call (exceptions go for important calls from work or family issues) and leave you standing in the middle of nowhere. People who, while you're out at a restaurant, will either answer their phone and talk loudly, or let it ring 5-6 times. Same with people who, despite the numerous reminders at the start of a film, will get calls during a movie, answer, and proceed to whisper loudly into their phones.

... Er, to sum up, I've got a lot of cellphone etiquette pet peeves.

Oh, and I also dislike when people leave their discarded drink cups (and other trash) in the aisles (or carts) at a store. That's just gross and unsanitary! >_<

Some of my pet peeves:

people that try to convert me to Christianity (I'm already a Roman Catholic, but they approach me with the assumption that I'm an evil pagan in need of being "saved")

people that try to convince me to vote Republican or try to make me feel like I'm mentally disabled for voting Democrat

people that talk in Spanish in my presence

men that greet me by saying "Howdy" (or, with a hick accent, "Hah-dy", which sounds like they're calling me a hottie) or "How's it goin'?"

senseless phrases like "the other day" (be specific!) and "same difference" (it's "same thing")

people that write "could of", "should of", "would of", or "must of" (it's "could've", "should've", "would've", and "must've")

men that ask me if I ever had sex (for the record, no)

my dad listening to polka music loudly

my mom calling me into another room to do something for her, when she could do it far more easily, if she'd bother to get off of the couch and away from the TV (get her a drink from the fridge, close the blinds when she's lying on the couch right next to them, etc.)

Billy Mays' commercials

Related to the "could of" thing...

People who use "there" or "their" instead of "they're"
People who use "your" instead of "you're"
People who say "haven't went" (I hear that at work a lot - "We haven't went to the movie yet")

I don't expect anything in return. I open the door just to be courteous.

Wow. Never thought I'd see that in an Archie comic. Nice find