The Brain Cell mail art project. Artists from around the world send Cohen images of their rubber stamp art, artists stamps, and other art and Cohen assembles them into these limited editions of 150. I've received two so far. He also sends along a list of the contributors and I have a goal to work through the list, sending out art. (It will be a slow process!) I also contributed a few of my hand-carved stamps, so we'll see what edition they wind up on.
Here's the second edition I received.