There are many. As a classicist, I am most obssessive about proper usage. I guess that the most annoying misues involves what I would call the "mising -n". Surely, you have heard many people -- educated or not -- do this: "I just watched a annoyinggly terrible movie last night", e.g... I have been hearing such mistakes more and more frequently of late, and I am wondering whether "an" is gradually dropping out of the English language as an archaism. I mean, I even hear it during "professional" speeches and such!