Unfortunately, I don't believe I had ever ran into any shiny Pokémon in Black nor White. I'm sure I would have if I tried, by chaining and whatnot.
Though, I did get myself a shiny eventually, which was transferred from another game. It was shiny Charizard. If I remember correctly, I'd first got the Charmander as an egg in Diamond version, which wound up to be shiny after hatching. I'm not sure of what the chances are of these kind of things actually happening, but I know I'm lucky. I love this Pokémon; its color-scheme seems very fierce, if you ask me!
Second shiny, which was also transferred, was Lucario. This was given to me by a friend in Platinum version, and have been keeping it with me on every game ever since. It seems to have good IVs, and its nature is great, too--Adamant.