check out a video of it here - revengineers@tumblr
My band typically plays along to pre-written LSDJ tunes but with the newer songs we've been working on there are a lot of sections where it doesn't make practical sense to use something pre-programmed, for example - sections where we jam a little bit and play it differently every time or where there are unusual tempo changes. So I turned an NES controller into a foot pedal.
I also modified No Carrier's Vegaplay code slightly to use with the pedal. Like I say in the video, his program allows you to press Up and Down to scroll through the tracks of an NSF file. I modified it so that way each button of the controller is associated with a specific track of the NSF. When you press UP, it plays the first track of the NSF. Pressing Down will trigger track 2, and so on.
Pretty basic mods but it's really useful.
If anyone wants one of these, I'll build it for $50. Just thought I'd throw that out there.