I went to themed wedding a few weeks back. Very cool. This would be epic.
Wouldn't you want to rig with a sound system so that when people park their cars it booms out "YOUR VEHICLE IS PARKED ILLEGALLY. YOU MUST MOVE IT NOW. YOU HAVE 30 SECONDS TO COMPLY!"
Or a motion activated sound module, so that when people pass in front of it! That would be epic. Some custom sayings relating to the wedding and presents. Oh... how I wish it would happen. There's a viral video in there some place!