Multi-console USB controller adapter?

[Timstuff]

I've recently started fooling around with a SNES9X on my PC again, and I got to thinking-- "It'd sure be nice if I had one of those USB SNES controller adapters". But, I remmebered hearing somewhere that they actually make ones that can adapt controllers from multiple systems. I'd seen one that can adapt PS2, GCN, and Xbox controllers to USB, but are there any like this for classic console controllers? It'd be nice if I could get out of owning like, 4 different adapters for the various system controllers I own that I'd like to hook up to my PC.