Hey, I forbear from correcting almost all the time, even though the restraint sometimes causes me almost physical pain. I inserted "sic" after "by" in my post because I didn't want one of you to jump on me--and I knew one of you would, given my reputation as the grammar Nazi here.
As for ending sentences with prepositions, it's still discouraged in formal writing, although even there it's tolerated when the alternative would be just too, too stodgy.