My biggest pet peeve is when someone ends a sentence in a preposition. I understand sometimes it is unavoidable, but really, sentences should never ever end with the word AT.
Another one of my annoying habits is the tendency to change subjects often, while having a conversation. Very few keep up with me.
"It's the little things; the details, that distinguish the Barbra Streisands from the Rosalyn Kinds."~Gilmore Girls~