I am interested in coming up with a few lectures from first-semester calculus that I can incorporate Mathematica into in a natural way. I have already written some code for a lecture on the $\delta\mbox{-}\epsilon$ definition of a limit, and I am looking for suggestions about things other people have done in their classrooms.
I would also be interested in knowing if anyone has done examples that "break" Mathematica. That is, examples that require human ingenuity that a computer can't simply compute the answer to.