If you want to create a bit of a stir, open up your digital billboard to the masses (may not be SFW) and let them post what they like. Better yet, post 20 of these on your wall. Grab flickr feeds and give each table in your restaurant a unique theme, or pop them up to match the menu for the night.
This is a small text-only example from one user, but of course the implications/possiblities are wide open. I can imagine customers or motorists rubbernecking to see what is up next. Why not let people send photos from their cell phone cams to billboards at stadiums?
I’m sure this has been done somewhere, but I found it pretty innovative. I know that loctite glue company did it once. It’s an idea that’s not terribly hard to pull off, and one could easily imagine interspersing ads within the text or image (2 for 1 margaritas!) and hanging it on the restaurant wall. Just until the competitors start posting on there (“aye, come next door for free beer!”)