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.

The Digispark is shipped fully assembled except for the two included and easy to solder headers.

Here are the specifications:

• Support for the Arduino IDE 1.0 and later (OS X, Windows, and Linux)
• Power via USB or external source - 5 V or 7-35 V (automatic selection)
• On-board 500 mA 5 V Regulator
• Built-in USB
• 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)
• 8 KB flash memory (about 6 KB 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

Schematic is https://s3.amazonaws.com/digispark/DigisparkSchematicFinal.pdf