VoCore is an open hardware runs OpenWrt. It has WIFI, USB, UART, 20+ GPIOs but size is only one square inch. It helps you make a smart house, study embedded system or even make the tiniest router on the earth.
Tiny Size: One square inch, easy to embed to devices.
OpenWrt: Easy to code, compile; stable system.
Low Cost: $20 for each, unmatched performance.
Interfaces:Hardware support USB, Ethernet, I2C, SPI etc.
OpenSource: Both software and hardware.