Hey there. /raises hand.
https://www.improvely.com and https://www.w3counter.com
Five figures a month, just me, I've written about my solo business a couple times in other Ask HN threads. Ten years ago (almost to the day), in my college dorm, I was looking at the Webalizer web stats report my web host provided for my blog, and thought "I could do something much cooler than this". So I did. I had built a few educational sites and threw some ads on them for a couple years before that, but W3Counter was the first service I actually charged a subscription for, and now I make a living building and selling this stuff.