Adblock Plus does that. Ad networks can in some fashion request their ads be unblocked, and ABP does some sort of review (I'm not sure how it all works, I don't use it).
I'm not sure, but isn't that review process basically a transaction of money? As in buying your way out of being blocked? That's probably the last thing I'd want.
In fairness, they don't just whitelist any old ad, there's ostensibly a review and guidelines that must be followed, but at the end of the day, it's still a colossal conflict of interest.