Digispark

[Prototyping⇐] Minimal development board. Compatible with and similar to Arduino.

Digispark USB Development Board
The Digispark is an Attiny85 based microcontroller development board
similar to the Arduino line, only cheaper, smaller, and a bit less powerful.
With a whole host of shields to extend its functionality
and the ability to use the familiar Arduino IDE
the Digispark is a great way to jump into electronics,
or perfect for when an Arduino is too big or too much.

DigiStump - Producer and Distributor (Portland, Oregon, USA)
BOXTEC - Lupsingen, Switzerland Digispark - [geekboy.it]