I read an article couple of years ago in a newspaper where they segmented one city based on how many schools, supermarkets hospitals etc were available in a certain area and then made a ranking based on that. The idea was mulling on my mind for a while and i finally got around making it not only for Tokyo, but for whole Japan!

Basically I gathered tons of different data sources from both freely available sources, Japan government's own open census data etc, laid them on top of the map of Japan and created weighted scores based on the results. Then based on the user's preferences (like do they want to see areas good for families, people living by themselves, do they use a car etc) it colours the map on 100m*100cm grids based on how good they are based on the values. Really good if you are for example trying to figure out a good place to live in a neighborhood and want to get a place that has a good access to supermarkets etc or even traveling a trip to the country :)