Adafruit 2000 PCB design board Adafruit Pro Trinket - 5V 16MHz AVR® ATmega ATMega328

The Pro Trinket PCB measures only 1.5" x 0.7" x 0.2" (without headers) but packs much of the same capability as an Arduino UNO. So it's great once you've finished up a prototype on an official Arduino UNO and want to make the project smaller. Like the Trinket, it has onboard USB bootloading support using a MicroUSB jack. With Optiboot support, you can either program your Pro Trinket over USB or using an FTDI cable. The Pro Trinket 5V uses the ATmega328P chip, which is the same core chip in the Arduino UNO, Duemilanove and Mini, at the same speed and voltage. The Pro Trinket is programmable using the Arduino IDE and almost all Arduino projects will work out of the box.

Price: 24.99 from Conrad Electronic