There are pedals that produce a vibrato effect , similar to what you do with your fretting hand (but not the same at all) , usualy these are called "Vibrato Pedals" , and they look like the distortion pedals ... They are turned on/off like the distortion , and they have settings of the depth and speed of the vibration (most Fender amps has this effect ).
Other pedals produce wide range of pitch shifting , like the "Digitech" whammy pedal , these look like a wah or a volume pedal , with few buttons on the side... They operation is similar to the wah pedal , except that you're controling pitch not tone.