I give a 'free', forever ongoing, astronomy class at the Senior Center. You don't have to be a senior to join, but you must join the Senior Center for $72/year, which you can defer for at least a month, until you determine that you want to continue.

I never give the same lecture twice. It would bore me. My lectures are well prepared, and contain enormous resources from the live web, projected from my laptop to a flat screen TV. It's all about gaining a perspective of your/my place in the universe.