Book publishers use banner ads on flies in Germany… via Wired.

Jung von Matt/Neckar lässt für Eichborn, den Verlag mit der Fliege, 200 mit Bannern bestückte Fliegen auf der Frankfurter Buchmesse starten. To promote their exhibition stand at the Franfurt Book Fair, Eichborn the publisher with the fly prepared 200 flies with an ultra light banner. The banner was attached with natural wax. After a short time the banner dropped off by itself. And the flies were not harmed.