In college, I had a relationship that began to turn sour when I received an email with the word, "wierd." I imagined saying to our future offspring I know this is how Daddy spells it, but it's wrong. This conversation would have to come at an age when said offspring should be believing that his parents are infallible, and the ensuing psychological trauma would take years of psychotherapy to repair. That stuff's expensive.
The ones that really get to me these days are "loathe to" and "phased" (to mean "fazed"). You see them everywhere--published books, weekly magazines. If you see me in a corner somewhere twitching, that's probably why.
For your grammar-nerd needs, I recommend After Deadline,* the New York Times' Stinkpot.
*Though please note that the recent entry implying there could ever be such a thing as excessive use of em dashes was obviously written by someone with unresolved psychological trauma.