We got this brilliant idea from Huifang's colleague Joe. He has a huge map in his house where he displays all of his keychains all over the map. Thanks for Google Map API, the realization of this idea can be implemented within a short time.
On the map I marked the purchases of the keychains. The beauty of the Google Map is that you can zoom in to a very detail scale to view the place. If the mark you want to click is blocked by someone else, simply zoom in and you will get a better view. Here is an example of how to play with it.
1. Click on the map, drag to move the map to any area you are interested in, say, Asia for example. If there are too many marks on the area, click "+" sign on the left upper corner to zoom in.
2. Click on any mark, for example, Fort of Nijoujou in Japan. A window of Fort of Nijoujou pops up. Don't click on the link.
3. Click on the "+" to zoom in around the specific mark. More and more details will be showing. Eventually you will see Google map displays something just like right: