I'd like to introduce a new Arduino compatible board, Microduino -- a smaller Arduino, only 1.0 inch x 1.1inch. And it's stackable, every Microduino board can be stacked together through Microduino defined 27 pinout.
I designed the first version of Microduino In November 2012, . The purpose was to build a small device to monitor server room temperature remotely. I split the Arduino-Uno circuit into two parts: the -Core circuit, functioning as MCU core, and the -FT232R circuit, communicating between PC and -Core. I stacked the boards together and connected temperature sensor in a standard hole board – BTW, Microduino is compatible with a standard hole board.
That was the very first prototype of Microduino, a very interesting experience. sorry, my soldering skill was not that good... share my interesting expeirence with you.
you can find more informatin in my facebook: https://www.facebook.com/Microduino