Need an arduino compatible board with a small form factor?  These boards work great for a variety of projects.  On board micro-usb means it is easy to program. No need to deal with an external programmer, just hook up a usb cable and go.

• ATmega32U4 running at 5V/16MHz
• Supported under Arduino IDE v1.0.1
• On-Board micro-USB connector for programming
• 9 x 10-bit ADC pins
• 12 x Digital I/Os (5 are PWM capable)
• Rx and Tx Hardware Serial Connections
• Size 1.3" x 0.7"