I've found working on http://editfight.com http://editfight.com to be extremely enjoyable. It's an online collaborative pixel art app with a fixed size grid. I

I've found working on http://editfight.com http://editfight.com to be extremely enjoyable. It's an online collaborative pixel art app with a fixed size grid. I made it for fun, and a few really talented pixel artists came and have made some awesome things. But the best part is that they have constantly given me feedback on what would improve their experience, and I've been able to add the features they're asking for within the hour, and it's been a really enjoyable cycle of that for probably 2-3 weeks now. It's so incredibly gratifying to see them appreciating and finding useful all the new features I keep adding for them. It's kind of addicting to keep improving the site for them and watching them use the improvements to make more and more amazing things. One of the biggest examples of this has been the "create a gif from the time-lapse of everyone drawing" feature which someone else suggested, and surprisingly only took about an hour to implement. It's pretty niche, but the few people who find the site and like it, they come back to it like every day and keep making incredible artwork in it.