A small bar on the outskirts of Paris, Les Chaises (The Chairs), came up with a clever mini advertising campaign. They asked all of their friends and family to save champagne bottle caps for them. 10 months later they collected 400 caps. They spent 20 hours fashioning them into colorful chairs affixed with a little card. They placed them around Paris and anyone who found them could return them to the bar for a prize (free pizza). All of the actual chairs in the bar are different and were acquired at flea markets, so the colorful mini chairs tie in nicely with that theme. Read more here.
(Photos from Les Chaises)