Trendsmap is an awesome real-time map of Twitter trends across the world. The map shows recent trends on Twitter live on a Google Map for any location that you choose.
Move the map and zoom in on any location and the Twitter trends shown on the map will update in real-time. The map is live, so if you leave the map zoomed in on one location you can see the trends growing and changing on the map over time.
When you click on a trend you can see the Tweets updating in the trends window. For each trend clicked on it is also possible to review a trend graph so that you can see the peaks and troughs of that trend over time, both locally and globally. Pictures that have been posted about that trend will also appear in the window.
If you click on the trend topic itself in the window (the large header at the top of the window) the map will change to a global view and show where in the world that topic is currently trending. About 500 cities around the world also have their own pages. If you click on a city name in the trends window you will be taken to a dedicated page for that city.