Is there any interest in a test platform to simplify testing and de-bugging with the Arduino?
If you imagine that you can insert your Arduino into a small fixture that holds it down and touches off on the bottom of the digital/analog pins. These pins could be multiplexed to a few BNC connectors and/or header.
This way you can connect an oscilloscope, logic analyzer or DMM to any of the pins on the Arduino without having to disconnect each instrument and move it to a new pin. The test system would allow you to decide which pins to connect to which instrument (via switches or GUI).
The motivation (at least in my experience), is that it is very annoying and messy to monitor signals on the Arduino given the female headers - especially with stackable shields.