The new board from Arduino, the Leonardo, is pretty much an Uno except that it doesn’t have a dedicated chip for USB communication. The serial port runs in the same chip that runs your sketches (the ATmega32U4). This means that if you reset the board you also reset the USB connection. However, because the serial port is virtual it means that the board can run as a (HID) keyboard or mouse.
The simpler physical wiring means that the Leonardo is cheaper ($20), but it also means that there’s less flash memory and some of the pins have changed, so Uno shields might not work with the Leonardo.
If the Uno footprint is just too big there’s the LeoStick from freetronics ($30).
- Guide to the Arduino Leonardo
- Boxall, John. (21June2012). First Look – The Arduino Leonardo. Little Bird Electronics
- Rogers, Jimmy. (22Sep2011). Arduino Leonardo Opens Doors to Product Development. Make Magazine