On/Off function (button). An example usage would be automatic cannon (cannon + torch) with On/Off switch.
Flashing torch function (slider to set the desired flash intervals: 0 = permanent on / 0< = flash interval). You can use this for airplanes, police cars, fire trucks to simulate flashing light or as a spark plug for engines.
This would include a block that when activated would play a certain sound. Inside the Mods folder there would be a folder called sounds. The user would put custom .ogg file in there and in the block tuner the player could select what sound the block would play from that folder. With this mod, you could make robots make robot noises, cars make car noises, etc.
This may have been requested before, but I would like to see place-able symmetry planes added/modded into the game. I think I speak for all builders when I say that it is a pain to replicate one side of a machine onto the other, and I notice a lot of other games have them implemented, so why not besiege?