Here are some ideas to get inspired by. The idea here is not to copy the same ideas, but get inspired by them and come up with something on your own. Good luck finding your idea!
Tamarafi is a Tamagotchi inspired pet whose fitness reflects the fitness of the user.
Activity finder for things on your subway stop. On My Line works with Yelp, MeetUp, and Google Places to recommend restaurants, museums, and events specific to your train line. You can connect with friends to share recommendations and the best part is, it works offline, so you can use it while you’re actually on the subway with no service.
Enhancing location-based experiences by associating memories with a location. Blacklight allows a user to leave a secret, story, or memory at a geotagged location so other users can access it through an AR reality treasure hunt.
Something like this, this, or come up with something even cooler!
The app presents nearby restaurants one at a time, with the fun, Tinder-style card swiping mechanic. After signing up, users can tell BiteSwipe what types of cuisines they enjoy, how much they want to pay, and how far they want to travel. These preferences are then saved to a database. When you're getting 'hangry,' you can bust out your phone, be swiping in seconds, and eating something new in minutes.
CodeHuddle is a web app for practicing and conducting technical interviews remotely. It introduces a real-time collaborative environment, with a shared whiteboard and customizable text editor.
For more ideas, take a look at: