The game Euro Truck Simulator 2 (ETS2) has a telemetry API to allow plugins access to the data about the in-game vehicle. I've created a plugin to send the data down a serial port to an Arduino microprocessor, which then controls the servos, LEDs and an LCD screen.
Video of it working is here:
You can download a copy of the plugin source and a pre-built plugin here:
http://downloads.silasparker.co.uk/ets2_dashboard_v3.zip (New version of code)
The code is now up on Github here: https://github.com/skyhisi/ets2_dashboard
Photo of final device made from MDF, the paint finish is terrible in bright light !
Video of how it works it here:
Fixed plugin built in wrong mode. Note, you may also need to install the Visual Studio 2010 Re-distributable package from here: http://www.microsoft.com/en-gb/download/details.aspx?id=26999