[Bob] has a USB page hit counter that uses an ATtiny25 to run a MAX7219 which drives eight 7-segment displays. It is easy to implement USB on an AVR using just firmware, eliminating the need for any USB to RS232 conversion. The host software is written in Delphi and sits in the Windows tray. The code examples seem simple enough to expand upon into your own display programs.
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.
We wrote about [Chris Anderson] before when he released the Arduino based autopilot. He has since crashed his first Predator UAV, due to an underpowered motor and poor control of the v-tail only steering. He has since released a pro version of the autopilot controller, and is modifying this UAV Predator drone kit to work with it. One ATMega168 processor handles flying and the other handles GPS navigation, but because they work together, it results in a fully autonomous drone. He also has a BlimpDuino version we have covered before.