Couldn't live without it Rated 5 out of 5 stars
Some websites are so cluttered with commercial messages that after enabling Adblock Plus with the right subscriptions, most of the page is gone! It's like a crash course diet for internet crap.
As for the financial question: for every kind of website, someone out there is always providing a similar website with similar content but with less annoying ads. If Adblock Plus is enough to put someone out of business (which is unlikely in any case) by robbing them of some ad money, that just means visitors will instantly migrate to a similar site that does not clutter itself so much. Everything is replaceable. The law of the internet is that users want control over what they see, do, and get online. It's one of the big reasons Firefox and open source exist in the first place.