Excluding Red Gyarados, A Shiny Pidgey that I found right before entering Vermillion in Leaf Green. I also found a shiny Ratatta like two wild pokemon encounters after that, but as I was in the beginning of the game, I had no money, and ran out of Pokeballs on it u__u.
Recently however, I was playin through my heart gold and I found a shiny Paras in Ilex Forest, which was pretty cool.