The core of the Arduino platform and the open source hobby electronics movement! From the official Arduino website:

 

“The Arduino Duemilanove (“2009”) is a microcontroller board based on the ATmega328 (which is an update from the previous 168). It has 14 digital input/output pins (of which 6 can be used as PWM outputs), 6 analog inputs, a 16 MHz crystal oscillator, a USB connection, a power jack, an ICSP header, and a reset button. It contains everything needed to support the microcontroller; simply connect it to a computer with a USB cable or power it with a AC-to-DC adapter or battery to get started.

“Duemilanove” means “hard to pronounce”... I mean “2009” in Italian and is named after the year of its release. The Duemilanove is the latest in a series of USB Arduino boards; for a comparison with previous versions, see the index of Arduino boards.”

Specifications

• ATmega328
• 14 i/o pins
• 6 PWM
• 6 Analog
• 16MHz
• 32kB Flash Memory
• 2kB RAM

Resources

• Atmega328 Schematic 
• GPS for Arduino in Less Than 30 Minutes
• Arduino with Radio Shack Parallax accelerometer
• Arduino with Radio Shack Parallax accelerometer
• Arduino with Parallax Sonar Sensor

Media