In a Public Space is a website/collaborative art project where people are invited to leave strange objects in random public spaces (this bullhorn to the left was deposited in a library). Then people write in with a picture of their object and the location they left it. I think it's pretty interesting - you know you've found things before and wondered, "How did that
get there?" Next time that happens, I'll wonder not only how it got there, but if it was part of a collaborative art project.
http://www.inapublicspace.com/ via Dark Roasted Blend