Kowtow, actually, according to the Common Errors In English web site.
Kowtow -- it's something I hate doing, and something I've had to do a few times in my life. Actually, I don't mind doing it when it's deserved, but it chaps me REAL BAD when I have to do it even though I was NOT WRONG. There have been exactly two times in my life that will stand out forever in my memory where I've had to do that. Talk about cementing the end of a relationship... that will certainly do it.
Anyway, I love books and web sites that give a nice comprehensive listing of common errors in usage. I may do an "Corrected Error of the Day" feature along with the "Fortune Cookie" thing. It's the least I can do, as I really am an English teacher at heart.