Well, call me a nazi, too. I feel exactly the same way--it's like nails on a chalkboard for me to read certain ungrammatical writing.
We all have certain things that drive us nuts--things that someone else wouldn't even notice. And I think most of us have little quirks/habits that drive other people bonkers. I even know what some of mine are, and I'm not sure how much of my continuing to do those things is just passive-aggressiveness on my part, ya know?
I'm a word geek, too, and lots of my job involves highly-skilled writing. Other people don't have to meet my standards, but it's my choice whether to spend time with people whose habits irritate me. Right? (She said, defensively.)
Oh, and I just edited this post for punctuation.