So, this is the only one I'm aware of online: http://www.raphnet-tech.com/products/n64_to_wii/index.php I'm specifically interested in using an N64 controller with my Gamecube. It's something I've wanted to do for a while, but never bothered to buy an adapter. I was just wondering if anyone on here has had any experience with this particular product, or any similar adapters. If anyone knows where to find the best quality for the fairest price, then by all means, let me know! Pretty much the only reason I want to do this is to play TimeSplitters 2 with a Nintendo 64 pad. Purely for nostalgia, you know. I guess it would also be nice to play Ocarina of Time with its proper controller.
I actually just started making one of those a few days ago so I'll let you know when it's complete, however I've built several other adapters by Raphael (http://www.raphnet.net/electronique/electronique_en.php) and have had 0 issues with them. It's really great that he makes the schematics for them and releases them along with the Hex files for free on the internet.
Sounds great! Keep me posted on your progress. I haven't purchased anything from that site yet, but it's nice to know it's a reputable source.