I think Unsplash was kind of like this until they were bought by Getty Images. Really loved they're way of presenting ads.

On a personal note, I tried getting into ads for one of my personal projects (a map of recycling points for my hometown), but Google declined my application because it doesn't have much content on it — though it's kind of absurd because people use my web app, to find locations on the map, not read content. I ended up not doing ads for now, and keep receiving "buy me a coffee" donations.