rarest and most desirable badges is the DefCon Black Badge. While the use of the badges are traditionally associated with DefCon, their use has spread to other conferences.

Pixelflut is a common activity at hacker events. It is a protocol for software to draw a canvas. Usually this is done in a client-server architecture with multiple clients who send individual pixels and the server displays. The clients then overwrite each other's images on the same server. There