Last February there was, in my opinion, a really uplifting thread with the same title¹. I'd like to see all the cool new things going on, and I'll steal the intro text from as89 to explain:
One where you don't care if it makes money or gets a lot of attention, but you are working on it regardless. I don't think I mean private hobbies, exactly, but projects that could or will be shared with others - you just don't care about the outcome.
¹ https://news.ycombinator.com/item?id=25992782
https://www.shlinkedin.com