Via jo(e) and New Kid:
1. Grammatical pet peeve. (Must keep my pedantry in check here) Easy -- using "at" at the end of a sentence, or a variation thereof, especially at the end of a scholarly presentation: "Okay, yeah, so that's where I'm at with my research right now." But actually it bothers me anytime, anyplace. I know it's perfectly fine to use prepositions at the ends of sentences, and other ones don't bother me at all. It's just something about the superfluity of "where I'm at" when someone could say "where I am," plus I hate the way it sounds.
I also don't like it when people use pronouns in the nominative case in contexts when they should be used in the objective case. Ex.: "She went to the store with Jane and I." The pronoun at the end of the sentence is the object of the preposition "with," so the correct usage would be "She went to the store with Jane and me."
2. Household pet peeve. When people kick off their shoes and leave them in the living room. Same goes for clothes. Cluttered counters and other surfaces.
3. Arts & Entertainment pet peeve. Some of you are going to be horrified, but...the acting in old movies and TV shows -- I'm thinking mostly 1940s and 1950s, but a lot of movies before and since then, too. The way they talk always sounds the same to me, with the same prosody, cadence, inflection, etc. Watch any episode of The Twilight Zone; that's how everyone sounds to me.
4. Liturgical pet peeve. I don't know. I hear that at some churches, preachers use PowerPoint in their sermons. That's crossing some kind of line.
5. Wild card. It irritates me when people I hardly know and haven't seen in years comes up to me and says, "You don't remember me, do you?" It just seems kind of pitiful, like the person thinks I'm higher up on the social ladder than s/he and is implicitly admitting it, but compensating for it by ensuring that I end up looking like a jerk if I don't remember the person, which I almost always do, and even if I don't, I don't give the person the satisfaction of my groveling; I just shrug. Jeez. Just say, "Hey, I think I know you from somewhere," or better, "I don't know if you remember me, but we had so-n-so's class together."
Bonus (things I do that become other people's pet peeves): Jonathan hates the way I correct other people's grammar (which I have no idea I'm doing, by the way). He says that someone might make a grammatical mistake, and I repeat the statement with the correct usage. It's hard for me to think of an example, so I'll use jo(e)'s. If someone says, "There's lots of apples in that tree," I might say, "Yes, there sure are lots of apples in that tree."