Ad blockers are often painted as the enemy of online publishers, but sometimes things are more complicated.

AdBlock Plus, for example, just announced that they’re working with startup Flattr on a new product that allows readers to pay the publishers who produce the content they read, listen to and watch.

As a result of the partnership, AdBlock Plus said it has also made a small investment of undisclosed size in Flattr .

Together, the two companies have created a new product called Flattr Plus. Like Flattr itself, it allows users to allocate a monthly budget that they want to pay publishers. Unlike Flattr, users don’t have to click a button to “Flattr” a website — instead, it will automatically track their browsing activity and distribute the money based on their engagement.

It sounds somewhat similar to the way a company like Spotify distributes subscription fees to musicians — except it’s not just for artists on a single website or app.

Plus, the question of exactly how to calculate engagement is a tricky one. You probably don’t want to reward a worthless article with a dumb-but-effective clickbait headline. You might also leave an article open for hours without actually reading it.

Ben Williams, who leads communication and operations at AdBlock Plus, told me that the product is still in beta testing (the plan is to do a full launch later this year) partly so the team can experiment with ways to measure engagement — it will involve some combination of factors like time spent and scroll activity.

Publishers will have to sign up with Flattr Plus if they want to get paid, b ut Williams said that if they’re don’t, the money they’re due will be held for them until they join the program . (Update: Williams said that actually, AdBlock Plus won’t hold the money — it’ll just tell them how much money they could have earned.)

The goal, he added, is to earn half a billion dollars in revenue for publishers next year. He doesn’t necessarily expect every AdBlock Plus user to volunteer to pay, but he predicted that many will — and when you’ve got 500 million downloads, just a small percentage of users paying a few dollars a month can add up.

In fact, he said the AdBlock Plus users who opt out of seeing any advertising whatever (even if it’s part of the company’s acceptable ads program), are the ones who “have been the most vocal in asking for solutions like this.” Basically, these users have told the company they don’t like any ads, period, but they still want to support publishers and creators. Now we’ll get a chance to see if they meant it.

Oh, and if you want to hear more about Flattr Plus and AdBlock Plus’ broader vision, I’ll be interviewing CEO Till Faida next week at Disrupt NY.