Touchless technology for interaction with devices such as Android tablets has been developed by Ootsidebox.
This is one of their demo videos that shows the technology in use. Hand gestures are used for control instead of directly touching the screen.
The project is open source / open hardware and based on the Arduino environment according to this article by Elektor who were visited by the inventor of the technology – inventor Jean-Noël Lefebvre.
The large brick-type open source PLC has 22 digital inputs, 6 analog inputs and 16 transistor outputs. It also features a SD card socket, 2 RS-232 ports, 1 RS-485 port, 1 USB device port and a JTAG port for programming and debugging.
All the source files including circuit diagrams for building the large open source PLC are available for download at the above link.
This small brick-type PLC open source hardware project is based on an ARM7 microcontroller from Atmel. The PLC has 10 digital inputs, 8 digital outputs, 4 analog inputs, a real time clock, RS232 port, RS485 port, USB port and JTAG port.
More information and circuit diagrams are available at the above link.