The AVR Butterfly, about the size of a credit card, is an inexpensive self-contained, battery-powered single-board microcontroller. It runs the ATMEL AVR ATmega169PV Microcontroller IC. The board includes a liquid crystal display (LCD), joystick, speaker, serial port, real-time clock (RTC), internal flash memory, and sensors for temperature and voltage. The board is the size of a name tag and has a clothing pin on back so it can be worn as such after the user enters their name onto the LCD.
The AVR Butterfly comes preloaded with software that demonstrates many of the capabilities of the AVR microcontrollers. Factory firmware can scroll your name, display the sensor readings, and show the time. The AVR Butterfly also has a piezo speaker that can reproduce sounds and music.
Read more about AVR Butterfly: Butterfly Projects