You know what really grinds my gears? People using 'u' in email instead of 'you' (or the even more ridiculous 'ur' which just reminds of me ancient Sumeria). I tend to be pretty particular about using punctuation and complete sentences in my email (you're all shocked, I know) but I usually don't care about people who take shortcuts. Except for 'u'; for whatever reason it just sticks in my craw.
And now you know.