This video shows a Guitar Hero 3 pedal controller in action. Designed by console-hacker guru Benjamin Heckendorn specifically for a customer, it allows Guitar Hero 3 to be played one-handed:
As Ben himself explains:
These replace the strum and whammy bar from a standard guitar, allowing you to use a single hand for the chords. What you do is use your foot and click your toes up or down to strum or navigate menus. To perform a whammy you lift up your heel – the spring loaded plate is shown in the up (full whammy) position in the photo, but normally your heel compresses it (no whammy). The pedal plugs into a modified Guitar Hero 3 Les Paul wireless controller. You can still strum the modified guitar but the whammy is only on the pedal.
(Cross-posted to my GameCritics.com blog).