I honestly don't know (there should be MANY, though I am kind of lazy right now to look into the subject... sorry. :P).
Anyways, I have got only two shinies so far... a shiny Floatzel, and a Kingdra. I obtained the shiny Floatzel upon searching for a REGULAR Buizel in Valley Windworks, because I REALLY needed a water-type Pokemon back then (my team consisted of basically a Machop, a Grotle, a Shinx, and that's pretty much it.)... and then, the very first Buizel I found in the entire game managed to be a different colored one! I obviously got extremely stunned, so I went ahead and caught it.
As for my shiny Kingdra, it was basically my friend's (he said that he spent around three or four hours fishing somewhere in Pokemon FireRed in order to eventually come up to a shiny Horsea)... he made up his mind and eventually gave it to me. The good thing is, aside from the fact that the Horsea was shiny, it also came with a Dragon Scale attached to it, so it wasn't too hard for me to evolve it into Kingdra. :3