2010 Development boards - Adafruit Pro Trinket 3 V

The Pro Trinket combines everything you love about Trinket with the familiarity of the core Arduino chip, the ATmega328. It's like an Arduino Pro Mini with more pins and USB tossed in.

The Pro Trinket has 18 GPIO, 2 extra analog inputs, 28 kB of flash, and 2 kB of RAM. Like the Trinket, it has onboard USB bootloading support, so you can either program your Pro Trinket over USB or with a FTDI cable just like the Pro Mini and friends. The Pro Trinket PCB measures only 38 x 18 x 5 mm (without headers) but packs 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.