Web advertising:
Ads have always been and always will be an unstable, ephemeral foundation for building large sustainable companies, with countless warnings from history. People that lived through the first dot-com bubble remember when advertising collapsed to almost nothing, bringing down a lot of companies that were thought to be successful. Ad blockers will undoubtedly be blamed when this happens again, with everyone forgetting that it doesn't require mass adoption of ad blockers to have ad rates collapse in value.
If not having your web pages look like a dystopian stroll through a Mong-Kok flea market from a crappy cyberpunk novel questions your fragile and manipulated morality, then simply don't use an ad blocker. But if you like a site and really want to reward it's proprietors for making something you find useful, instead of trash talking me on your favorite ad-driven social network job, why not spend the resource of your time to send them some actual money? We'll all be better off for it. Why? Because when you do that, and they build their business that way, you become a customer, not the product.