This is old news, but I didn't see any previous threads when I ran a search.
A few months ago, someone by the name of Mark Feldman was able to successfully modify an old school NES and SNES controller to create a wireless controller that worked with the Wii's Virtual Console.
A few months later, he posted the instructions on the internet so we could make our very own wireless controllers. I was wondering if anyone here has heard of this, and more importantly, if anyone here has made one. I'm thinking of trying this out, and thought it would be cool if there was someone here who has already given it a shot.
You can find Mark Feldman's website here.
EDIT: I have purchased my used SNES controllers and will begin disassembling/reassembling as soon as I receive my other components. Since I don't have much experience in this sort of thing and since I imagine many of you don't either, I will be updating this thread with simplified instructions as I figure out different aspects of the process. Stay tuned!