Misty flip was named by Ali Goulet, a professional snowboarder. "It was just one of those silly things. Back in Vermont there was a bunch of guys like G-man and Brushie and these other guys who made up their own weird vocabulary. You know how they're weird, like "bappys" beers and whatnot. Everything was misty, like misty woods. So anyway I just thought it was a weird flip, so it became the misty flip."
Cork is pretty self explanatory - the rotation is like a corkscrew.
Rodeo - Comes from snowboarding, but I don't know who named it or why.
Bio spin - unsure on origin, was originally a name for a flat spin.
McTwist - Named for skateboarder Mike McGill who invented it.
D-Spin - Named for Mike Douglas who invented it.