I've made an addon-program for game streamers, one day I decided to go "heck", why not ask some money for a license.
I can't really say I'm making a "living" off of it but for a student I do have a /really/ nice income.
It's a /very/ specific application though. It swims along with the bigger fish like Open Broadcaster Service and xsplit, when they go down, I go down.