None... well, besides Gyarados, obviously.
Only shiny that I've ever caught in my lifetime was a shiny Rhyhorn... in Leaf Green. As far as GSC, though, no such luck. Of course, I've never really tried all that hard in looking for them, but if I did, I'd probably be rotting away somewhere right now. They are the kind of things that you just have to be lucky enough to run into, and so far, in the GSC generation, I have yet to encounter a shiny Pokemon.
I still love my shiny Rhyhorn in LG, though. You can't take that away from me. =P