What drives me nuts is the rampant misuse and abuse of the word "literally" that's sweeping our nation like a plague. It's like a knife in my soul every time I hear it now. And I hear it all the time -- some people use it in practically every sentence [Haha, I just heard my roommate say it as I was typing that sentence. He's one of the worst offenders.] Gone are the days when you could say something like, "You literally drive me nuts," to, I dunno, a guy who delivers pistachios, and have it mean something.
Also, people who pronounce words to make them sound French, like "homage" or "niche." But that's a losing battle, because it's rare that I hear those words pronounced correctly anymore.