The RepRap project, which is a printer that can make components using rapid prototyping technology, and it is designed so that it can eventually self replicate. Has released a new breakout board for the Sanguino that provides access to all the pins as screw terminals. The Sanguino is an Arduino compatible board based on the ATmega644P chip. You can populate the full board with all the components and have a fully functional single board. You could populate only the screw terminals and plug your Sanguino, and use it as a breakout board as well. The board design is released on Google Code.