Lula Cafe in Chicago. They have a pile of pinback buttons tacked to the wall in a delightful cloud of wonderment. I love the idea of something other than a rectangular object hanging square on the wall. The texture of the buttons popped out at different heights was really fun. So here's how I recreated it in a way that made sense for my house.
I bought up all the little round wooden wafers I could find in town (had to visit all three craft stores)--I chose 1", 1.5", 2" and 2.25". I drilled a hole in the center and drove a white finishing nail through it to create little round pins. The finishing nails had a lot of tooth. I wanted to make sure they would stick well into the drywall.
Next I created some templates out of cardstock by drawing around the circles to create one of each size. I used the templates to draw circles and cut them out of magazines. The color for the room is black/whitegray and the walls are seafoam. We're using splashes of red throughout the house and that room (office) has a big bright red Ikea rug in it as well, so I looked for magazine images with variations of those colors.
Yep, I just poked them into my wall! If you're squeamish, they could be tacked to board and hung on the wall, but I don't do things half way. I created a sort of organic cloud shape. Voila!