This word would describe a car, light switch, computer, etc. because they can all be turned on or off. I thought of toggle-able, but that doesn't sound right on a couple levels.
Edit: I am hoping for something specific to the idea of 'on' or 'off', if it exists. For example, suppose you have two possible colors for some text in a website, lets say red and blue. You could have a button that toggles the text between the two options, but you wouldn't necessarily say that one is 'On' and the other is 'Off'. I feel that 'toggled' is more general and can refer to more states than just 'on' or 'off'.