This gorilla marketing campaign by Heckler Associates in Seattle wins my "Best Damned Non-Traditional Marketing Campaign" award for 2009. It was designed to help a local restaurant sell more clam chowder. The company did everything, including inventing a fictitious clam entrepreneur, raising fake 1950s-era billboards from the bottom of the ocean, inventing old letters, invoices, blueprints and other documents in fabricating the elaborate hoax.
It worked. For $250,000 they got lots of media attention, raised customer counts by 5-10 percent, and more than quadrupled sales of clam chowder.