I built a coordination site for NGO/volunteer orgs in Puerto Rico who are responding Hurricane Maria. The goal was to replace paper records and tracking with something a bit more modern. The project was fun, had a direct impact on the ground and really helped me develop some new skill sets. Plus it ended up getting me a promotion in the end which doesn't hurt...

Besides that when I can write an R or Python script that automates a process for someone the look on their face is always amazing. What can take them half a day can then be accomplished in a minute or two...