The Biggest Drawing in the World, a self portrait of the creator, was made by sending a suitcase with a GPS tracker around to various sites, using DHL. (via Core 77)
Update: Lots of people are calling BS on this one, including Atanas, who insists the sailing routes are bogus, and others, claiming the GPS won't transmit through the case. Fooled by a viral for DHL? Even so, not a bad one, as viral videos go.
Update 2: Yup, it's BS. What I find disappointing about this is that it could easily have been real--sure, the lines might not have been as precise or expressive, but he could have done it. I'll bet DHL offers to foot the bill. But come to think of it, I don't know how I feel about all that carbon for one project like this.