Watch the Whammy Foot online guitar lesson by Jennifer Batten from Rock Sauce For Lead Guitar
The whammy pedal offers you a hands free method to bend notes or chords. My favorite setting is to bend down a whole step, which emulates the sound of using a slide on the guitar without having to go get a piece of glass or metal to slide over your finger. So, you have the use of all of your fingers, plus the added advantages of being able to instantly detune the whole guitar to open D, and access natural harmonics that are normally not available to guitar players. It also allows you to bend strings while two hand tapping, since you're not able to get to the whammy bar if both hands are busy. You're not limited to a just whole step bend setting. You can program the whammy for a variety of different intervallic jumps.