Lichee Pi Zero is a micro, extensible, open source linux module/computer.
It is only a little longer than SD card, and can be plugged to breadboard directly.
Here I will convert it into a phone(pcb design). I do like that its extremely small.
More info on the Liche Pi Zero go to the devs funding campaign https://www.indiegogo.com/projects/licheepi-zero-6-extensible-linux-module-on-finger-wifi-diy#/