"A new movement has combined geocaching, file-sharing and graffiti into a form of urban interactivity that feels illicit. It may also a be a sign of things to come."
Read more: http://goo.gl/tGi7X
This reminds me of an idea Dave Ulmer had for geocaching back in 2000. He called it a cyberstash. Back then, you had to go home and retrieve your cyber prizes from the Internet. Now, you just plug in the USB-drive and retrieve your cyber prizes at the waypoint.