Sarah Hepola at The Morning News has a compilation of extremely funny (in that ironic sort of way) instructional videos. If you're one of those "teach by counter-example" type of people (like me), these are useful for kickstarting class discussion about tech comm and instructions. (I've been using the Finnish instructional video on disco dancing for years. It works even more effectively if you discuss usability testing before you show the video and ask several students to come to the front to be usability testing subjects.)