App Wanted to Display Large Scrolling Text

At a very crowded & noisy gig a while ago I saw someone use their iPhone to display a message to someone about 10 yards away (who he couldn't get to easily). He did it by typing the message into his iPhone and then holding the iPhone up & it displayed the message as large scrolling text (IIRC it was something like "2 pints bitter, glass wine & some nuts"). I haven't been able to find something (pref free) that can do that - any ideas?