A web-app built on my own time at the request of some Berkeley MBA students for the Launch startup competition.
I got to play with the Google Maps API as well as perfect my quick website deployment strategy: launch a Rails app with AngularJS, deploy it on DigitalOcean and use WebBrick to serve it on port 80. Use rails scaffolding and the Beautiful-Scaffold library for making acceptable-looking, functional pages.
This business idea was actually selected as a finalist for the Launch startup accelerator. However, we turned down the option of growing out our idea as the team was unsure of our ability to commit time to it over a semester.