Two friends and I run http://domai.nr/ http://domai.nr/ on the side. We launched it 5+ years ago (here on HN, I think), and it's generated revenue ever since.

Two friends and I run http://domai.nr/ http://domai.nr/ on the side. We launched it 5+ years ago (here on HN, I think), and it's generated revenue ever since. Our first goal for it was, "can it cover the cost of its own domain?" Which is an absurd $500/year because that's what the .nr registry chooses to charge for registrations at their top level. After reaching that goal, our next milestone was the .nr plus California's silly $800/year LLC tax, which we also eventually hit. From there we've set more milestones, such as "occasional nice meal-profitable" to "monthly rent-profitable" and beyond. It's also inexpensive to operate, because it's stateless.