I released a free app called Tokyo Ramen Map a few weeks ago on the Play Store. It is a simple map application showing all the ramen restaurants in central Tokyo, along with ratings. I built it for my needs so it is quite bare bones. The main point was to make it work offline since I don’t have a data connection outside my apartment.
It uses cartographic data from the OpenStreetMap project, rendered on the device through the Mapsforge library. The positions and ratings of the ramen restaurants come from scraping the RamenDB website. All the code for the app is open source and available on github. It can also be used to generate OpenStreetMap-based apps for any city, with the option of pre-loading points (like the Ramen app) or letting the user add their own. As an example of the latter, I have released apps for Tokyo (Tokyo Offline Map), without the ramen shop layer, and Geneva (Geneva Offline Map).