I've got quite a few, actually.
--I
DESPISE being informed of important things last-minute (as in less than 24 hours notice). If it's sometimes I have to do, I will usually do it anyways, but still.
--I have a certain place for almost everything I own (books, movies, music, etc.), and if something is not at a place that I want it, you can expect a rage fit from me.

Seriously, though, I'm very organized about things, particularly any objects in my bedroom.
--Unless absolutely necessary, DO NOT pressure me to do something I have to do. While it is sometimes helpful, as I have found out many, many times, I still get a bit irritated over that fact.
--If anyone is a jerk towards me, I don't care if you tell me not to tell anybody you did something stupid, I WILL tell someone trustworthy.
I could list quite a few more pet peeves of mine, but those are some of the toppers.