Rental no-talking lasers at events
Ok, this isn't entirely serious but...
Just got back from a concert by Andrea Bocelli, which was 75% italian opera and then the last 25% his pop stuff. Curiously the conductor told the audience when they switched about how he was getting to the pop stuff we had been patiently waiting for and the audience applauds and laughs. If it's really that way, it's interesting to wonder if they still make more money doing mostly opera because opera commands more money because of implied lesser demand. (Expensive seats ran to $275 and that was a fair bit of the floor.)
Anyway, perhaps it was the different type of audience for Bocelli, but there was some talking, and people holding up cell phone cameras to take pictures, with the odd digital camera flash. It was a bit strange, mind you to see a crowd of people in fancy dress clothes and 3" heels at the hockey arena, eating nachos from the concession stands and watching opera.
Because in my mind you should not even have to think about shushing people at a classical concert. (I don't think you should have to at a movie either, but that battle's long lost.)
So the non-serious suggestion for all sorts of venues. Give people (with a $5 deposit) a portable laser that projects a small no talking symbol. Perhaps the word "TALK" with a circle and line, something you can do in the small resolution of laser pointers. When somebody talks (or does the cell phone thing which is distracting now just for the super-bright backlight) you beam the laser on them somewhere they will see. Ideally lots of people do it.
Of course, if people did this it would be distracting it itself, defeating the purpose. It only works if it is temporary, and people learn the lesson, and you don't have to do it again. A digital follow-spot that identifies bright lights and sounds would also work. Pea-shooters might be better but how will people know what the message is?
Speaking of which, why don't more cell phones dim the backlight when they are in a dark room? It would save power. (Though I know people now use these as flashlights of a sort.)