I often hear stories about people dropping their side projects as soon as it costs them money to run. I've done it myself many, many times. Sometimes the project just isn't interesting enough or you're not excited enough to justify the cost.
But I want to learn about some side projects that the dev community runs out of love, even though it costs them time (and maybe even some money) to keep it going for little to no return.
So, if you have a side project that you don't monetize but keep working on and make sure it's running, what is it?