i have evolved my shit wave sync cable to something that will sync just about anything with anything else.
here are a few ideas of what it will be able to do when its finished:
this is the pitch sync, one gameboy controls the pitch of another
http://www.youtube.com/watch?v=zn-xOAfz6Rc
this is audio sync, one gameboy controls the audio output of another
http://www.youtube.com/watch?v=5fwNy4-gJyU
this is self sync, one gameboy controls its own audio output
http://www.youtube.com/watch?v=hqEjVRW3z_o
there is a lot more to come and i hope to build a full waveform editor into it so that i can get some really weird sounds out of it smile