Trendero is a new Google Maps based application that allows you to report on and follow trends around the world. Users of the application can report local trends and search the world to find what it is popular in other locations.
You can browse the map to search for trends in a number of categories. For example you can search for trends in music, film, books, fashion etc. Trends are assigned a trendiness score based on several factors, including: who reported the trend; how recently the trend was spotted; how actively users are updating the trend and how many people are looking at the trend.