Twitter Heat Maps
Twitter Heat Maps takes a snapshot of all the Tweets in a particular area every ten seconds. The application then produces a heat map of all the Tweets on a Google Map. Currently heat maps are being produced for Tokyo and Osaka.
By creating these Twitter heat maps the creators hope to be able to observe which parts of a city are popular at different times of the day. Here is a video of the heat map for Tokyo over 24 hours.
Looking at the heat map for the whole day it is possible to observe a movement from the suburbs in the morning to the business areas during the day and then to restaurant and entertainment areas in the evening.