I have a ton, but now that I have to think about it I can't
I guess one big one is when my boyfriend leaves the toilette seat up. I mean, seriously, what's the big freakin deal?
*edit* I just thought of something else that bugs the hell out of me. When people park in handicap spaces, or just pull right up to the curb in front of my store and "run in real quick". And when people take up more than one space on purpose just because they have a "nice" vehicle. Pisses me off.