If you've ever used a controller to trigger effects, then you're familiar with toggling - press the button once to turn on the effect, and again to turn it off. How about making an effect that's only on when you hold down the button, and then turns off as soon as you lift your finger? These kind of momentary effects are great for a live setting or for home/studio jamming, but often depend on whether your MIDI controller has a "momentary" setting.
In a new tutorial, Ableton Certified Trainer Aaron Zilch demonstrates how to set up momentary effects in Live using Dummy Clips - a method which works with any controller, or with your computer keyboard: