I haven't; I work as a producer - in practice, a manager - for a small TV show that's currently on hiatus due to money problems. I'm not a business person or an entrepreneur, and pretty terrible at making money (just don't have the instinct for chasing it), so the only business I've 'launched' is my freelance work. My skillset is rapid technical ability, creative communications (ranging from manuals to PR copy to video editing), and crisis management. I get lost or cause trouble in big organizations, am a valuable catalyst/trauma specialist in startups, and do best at assembling things where the pieces are lying on the floor and everyone else is confused about what to do next.

tl;dr - unworldly troubleshooter.