We've had some discussions here about structuring sales prices based on future revenues (e.g. revenue targets, revenue sharing, etc...)
An article related to that, of course in valuations most of us will never even dream of hitting
Club Penguin Misses Goals, Giving Disney a Half-Price Deal
LOS ANGELES — Club Penguin, the subscription-based online community acquired by the Walt Disney Company in 2007, has failed to meet profit targets that were tied to $350 million in payouts to the Web site’s creators.