Photochaining...

Photochaining is the art of leaving memory cards in public places to be picked up and used by others, who then continue the cycle and do the same thing. It's an interesting concept (who doesn't like playing detective and sneakily peering into the lives of others?) made even cooler by its use of the web. When someone finds a flash drive, he/she uploads the pictures to the photochaining blog along with where and when he/she found the drive. This way you can see just where and when the chain is spreading.

The cost of flash drives is making this very very inviting...