The ongoing Four Icons project by Kyle Tezak. I love the simplicity of this project, and the colors he used for each of these:
"Trying to capture the essence of an object or idea with only a few lines and at the same time maintaining its elegance is pretty much design in a nutshell. That’s what so great about icons, they’re tiny poems. I decided it would be a fun project to attempt to sum up some of my favorite books, movies, historical events, anything, with just four icons; the meat and potatoes."
(images via Tezak)