Interestingly, the supporters who attended the McCain rally in Fairfax, VA today were asked to volunteer -- during the event.  Little pieces of paper (like the one below) were distributged to everyone in the crowd. 
Form-1.png picture by MattLewis01

Each piece of paper included two names and phone numbers.  Audience members were asked to phone these two people -- from the event -- and ask them whether or not they were supporting McCain.  These cards were then to be handed back to the campaign...