The Evil Mad Scientist Labs folks made badges for the Open Hardware Summit. Naturally, the designs for the badges are, themselves, open:
Naturally, the badge itself is an example of open source hardware. It's constructed as an extra-thick circuit board, in the shape of the Open Source Hardware logo, with plated gold finish. It was made with our usual open source toolchain, including Inkscape and gEDA/PCB, and the design files are hosted at the Evil Mad Science Wiki.