Ricocheting off Claymore's (sorry) idea - I don't know if the focus of what you suggest is on sound people or performers. I think an introduction to using sound equipment for musicians who haven't had much experience would be a good thing. A "Meet Mr. Microphone" workshop.

Last year, I was a bit afraid the varying volume of my singing would blow something up. Luckily, I'd had a very small bit of experience with my computer microphones. I don't know if this sort of thing would be possible or not, but if it is, it would be a GREAT opportunity to practice not popping p's, hissing s's or breathing directly into a microphone. Good to see how various factors in singing or playing can come across when using amplification and maybe get some tips on controlling those factors.

I don't know about anyone else, but I've often longed for a chance to experiment with microphones in a non-performance situation. It would be even better to have a knowledgable person explaining stuff. I also wonder if there are any Sound Guys who've found themselves wishing someone had, at some time, explained things to performers. You know - nipped certain bad habits in the bud.