Jonathan is a music student getting his Masters and he's putting on a chorale recital soon. He would like to create a way for his audience to interact with their smartphones, follow along with the score, and more. He's using QR codes that link to DropBox files of the scores and wants to set up a mobile chatroom. Leo says that the music group Umphrey's McGee is really good at stuff like this. They also do stuff like take requests and sell the concert on USB key afterwards.
Leo says the easiest way is to get everyone to use Twitter with a set Hashtag (#). It will make it really easy to search for all comments during the concert. Facebook will work as well. If they don't have an account for that, he could set up a Google Voice number and have them text their thoughts.