I think a music player might be a good one. I have my older music on computers at home or stored in cloud storage (not media services). I could imagine putting

I think a music player might be a good one. I have my older music on computers at home or stored in cloud storage (not media services). I could imagine putting together a web app, mobile app, or both to be fun and interesting. Maybe fork an existing opensource project so that you get full control of expressing your preferences.