Built a few things to teach myself new stuff, the ones that are still online are:
https://play.google.com/store/apps/details?id=com.bitmasch.b... - Wanted to learn a cross platform app framework. Built a simple game that would help my niece get better at basic addition, subtraction, multiplication and division. Made with Apache Cordova. She only played it a few times, but her dad (my brother) ended up getting hooked on it for a while, beating other people's high score with 50-100 points every time someone beat his highscore.
http://p2pool.jir.dk - Wanted to get some experience in building a crawler and was interested in p2pool cryptocurrency mining at the time, so I built a p2pool crawler. The site does have adsense, but it doesn't really make any money.
https://play.google.com/store/apps/details?id=com.bitmasch.b... - Wanted to learn a cross platform app framework. Built a simple game that would help my niece get better at basic addition, subtraction, multiplication and division. Made with Apache Cordova. She only played it a few times, but her dad (my brother) ended up getting hooked on it for a while, beating other people's high score with 50-100 points every time someone beat his highscore.
http://p2pool.jir.dk - Wanted to get some experience in building a crawler and was interested in p2pool cryptocurrency mining at the time, so I built a p2pool crawler. The site does have adsense, but it doesn't really make any money.