I stumbled across this site today and found it quite interesting. I spent a good bit of time clicking on a lot of the words to see if I have been using them correctly. There are also some supplemental pages/links at the bottom of the page that are also interesting. I thought many of you would find it to be fun and informative as well. And, after you take a look, if you'd like to post which ones you've just learned you've been using incorrectly all this time, post away.
http://www.wsu.edu/~brians/errors/errors.html#errors
http://www.wsu.edu/~brians/errors/errors.html#errors