I stumbled upon this particular thread through Google, and found that the subject is right up my alley. So much even, that I registered just because I wanted to contribute. Sad, I know.
Aside from many of the common irritations already mentioned, I feel obliged to add those that have been one of my major pet peeves: the 'would of', 'could of', and 'should of' combinations.
Someone already said in an earlier post that native English speaker don't have an excuse to mix words (I think it was in relation to you're/your), with which I wholeheartedly agree. But it frightens me that someone like me has a better grasp of the English language than people who have spoken it their entire lives.
I could go on for hours (or miles, measured in posts), but I'll end here. For now.
