As a developer, I've worked on some side projects. Some are abandoned, some are online, and others are just prototypes. You can find all of them on my GitHub account, but here are my favourites!
Badger - Gamification platform (Github)
Badger is a web gamification platform to motivate your team with badges, adventures & other cool stuff!
This project has been developed as a personal side project for the company I work in. Initially used to unlock some dumb rewards internally, it has since been open to our community, in order to unlock some work-related badges.
You can install a Badger instance for your own community (a live example here http://badger.akeneo.com). I haven't work on it since several months now, but I really think a gamification platform could be something great.
Odin - Celestial Planet Generator (Github)
Mainly developed for a web-based game, Odin is a libray to procedurally generate some 2D celestial bodies. Making "art" with code is really interesting. Rendered planets are far from being perfect, therefore some of the generated pictures aren't that bad, and there is a lot of room for improvements!
Some pictures generated by Odin: