You can build online community of your neighbourhood, by providing them, latest news, events, messaging, courses available in your neighbourhood etc.
Build an app to serve your residents of your private apartments. Update your residents with whats going on within your apartments, update then any latest news, events happening in your apartment etc.
Build an app for your church, and bring the people together. Publish audio / video sermons. Allow them to request for prayers. Update them with latest news, events of the church.
Build an app to communicate and regular updates of your kids to their parents.