Check out this post from Ankesh Kothari about a Bombay nightclub that stamps a public service message on the hands of entering patrons.  DUI lawyers, you've got to see the picture, and think about paying a bar to use a rubber stamp with your phone number on it to stamp the hands of everyone who enters the bar.  When they get pulled over later that night, they'll know who to call.  Not sure if ethics-safe, but inspiring nonetheless.