Logic Board is an Android app you can use to simulate simple logic circuits.
I had to make some logic circuits for physics a while ago. To learn wiring electrical logic, we have something we call a 'system board' at school. These boards contain a number of logic gates, a pulse generator, some LED's, a counter and some other components. You can connect these components with wires. This way, you can create simple logic systems. While working with these boards, I discovered it's real fun to mess around with logic circuits.
Therefore, I made this Android app that enables you to simulate some simple electrical circuits. To make it a little more exiting, I integrated some Android Hardware including the flashlight, the volume +/- button and the return button. Moreover, some sensors, including the proximity sensor, the light sensor and the microphone, can be used as input. It was quite difficult but I also managed to save all 'boards' in JSON format.
If you have an Android device and you know a thing or two about electrical logic; install Logic Board, it's fun and it's totally free!