Wikipedia is great for finding out bits of trivia, but not to use as a reference. It can be very tempting for students. However, sometimes the links to source material at the bottom of the page can be a step in the right direction.
This site has its uses, but too often I am faced with a list of results that I can't access. The college library is a much better way to find articles.
Even though teaching root words seems to have fallen out of favor, I think they are a great took. They come in especially handy for standardized tests such as the GRE.