There is (was?) a service that did this. I had it on one of my blogs a few years ago. People could use it to donate as little as a penny, and the donate button appeared on each article.

I was very surprised how generous some people were. 10¢, 20¢, or more. But in the end, even with tens or hundreds of thousands of views, the article that got the most donations still only racked up about eight bucks.