I have always thought it would be cool to video tape some of the best scenes during a dress rehearsal, compile them into an advertisement for the show, and see if you can work out a deal with your local movie theater to show it during the previews for the week leading up to the show.  I have never done this before, and I doubt that the big chain theaters would go for it, but many communities (including my own) still have a privately owned theater around and I bet most would do it in exchange for some advertising in the playbill