The Most Valuable Information

What is the most valuable knowledge in the world? Let's say I rule out a few categories:
Psychic knowledge of the futurePsychic mind readingTrade secretsCompany insider informationNational security secrets, such as war plans

Fair game is any sort of information that could be collected with some amount of time and effort, even if it isn't being collected at the moment. And it has to be legally obtained.

I'll take a stab at the question just to prime the pump. Suppose you formed a private online club