Back in 1990, I stumbled upon a fun store in San Francisco that specialized in products for the newly revitalized ecology movement. (Remember 50 Simple Things You Can Do to Save the Earth?) I bought a reusable linen coffee filter -- for years, I drank coffee that tasted like a t-shirt -- and a set of paper stencils and glow-in-the-dark paint to put an astronomically accurate map of the night sky on my ceiling. The store also had a really cool paper fastener, which punched and folded tabs on your papers to hold them together without staples. I was a grad student and the stencil was setting me back $25, so I didn't buy one. But then later, when I had money, I couldn't find one.
Then last weekend, I found this as in impulse item while waiting in line at the Container Store. I bought two. It only fastens 5 sheets of paper, but it's just so cool. It punches a little tab and slit in your paper, folds the tab back, and tucks it into the slit. Other models are available at the manufacturer, Made By Humans.