Support for the Arduino IDE 1.0+ (OSX/Win/Linux).
Power via USB or External Source - 5v or 7-35v (automatic selection).
On-board 500ma 5V Regulator.
Built-in USB (and serial debugging).
6 I/O Pins (2 are used for USB only if your program actively communicates over USB, otherwise you can use all 6 even if you are programming via USB).
8k Flash Memory (about 6k after bootloader).
I2C and SPI (vis USI).
PWM on 3 pins (more possible with Software PWM).
ADC on 4 pins.
Power LED and Test/Status LED (on Pin0).
Size: 1.8cm x 2.6cm .