Evil Mad Scientist Laboratories made these ATmegaxx8 breakout boards that double as business cards. Windell writes:
Our design goals for this project were (1) to make a printed circuit board version of the minimalist target board for the ATmega168, encompassing a place for the chip and a connection to the 6-pin ISP header, (2) to make a minimal and inexpensive circuit board platform that you could use to deploy a single AVR somewhere with without much fuss, (3) to encompass the capacity of a breakout board, giving extra holes to tap into each pin of the AVR and provide labels for every pin, (4) to fit in some small amount of flexible prototyping space, (5) to make it all fit into a neat business-card form factor, and (6) to release it as an open-source project.
Brilliant, and I can’t wait to trade business cards with them! – Link.