The Dunlop Crybaby Wah Wah Pedal is the most versatile effect you can use.  With the Crybaby guitar pedal you are able to control the sound of the guitar with your foot, making screaming, crying and moaning effects.  The Dunlop Crybaby can also be used to make an alternate rhythm with your foot.  This guitar pedal is great for chords and lead guitar playing.  I would say this pedal is a must for any pedal board.  Some of the guitar greats like Jimi Hendrix, Eric Clapton, Jeff Beck, and Stevie Ray Vaughan have done amazing things with the Crybaby Pedal making the guitar sound almost human.  This is a must have pedal for your pedal board, you will have more fun with this pedal than any other pedal on the market.  Check it out here at amazon Dunlop The Original Crybaby Pedal