I have high hopes for Quora (one of the YC portfolio companies) because they are trying to make accessible this sort of locked-up knowledge.
EDIT: Forgot to say I agree with you on the forbidden knowledge in organized crime being interesting. I've seen some myself and it's wild stuff. Atavist needs to do one on Berlusconi in Italy. ;)
Stackoverflow: Alexa Rank 52
Both have high-quality answers to numerous topics. One is both free and ahead of the other. Results speak for themselves, eh?