Area Code Map
Google Maps makes extensive use of Javascript and XML, and any developer with an API key is free to create their own use of the data and interface. It offers a way of organizing and visualizing information geographically. Since the API was made available, in June 2005, lots of cool ways to use it have been invented. Some fall on the fun/silly end of the spectrum, and some fall on the brilliantly useful. I’ll let you decide on which of these are which.
1. World Clock-Qlock is a quick way to find out what time it is anywhere in the world. Type in the name of a city, or mouse over a portion of the globe and see a box up with a real time clock in your local time. There is also a premium paid version which has a currency converter function, as well as lots of other goodies, like RSS feed reader, alarms and more.
2. 
Acreage – Google Maps Planimeter Is a cool little page that lets you figure out the acreage of an area (or square feet, square milage, square kilometers or hectares), by clicking on 3 or more points. Ever wanted to know how many square feet your favorite park is? Try it. By the way, a planimeter is a mechanical drafting device used by cartographers and surveyors to compute the area of a graphically represented flat region.
3. Taxi Fare – 
Taxiwiz figures out the cab fare for 21 popular U.S. cities. Enter the start point and destination and it will calculate the fare plus 15% tip. This one is a natural for smartphones, so naturally there is also a mobile version of each city map. The creator of this site, Mike DeGraw-Bertsch, lives in New York City and he’s posted some good NYC taxi tips, as well.
4. Volcanic! Volcanoes of the World
5. Disease Outbreaks Healthmap is a rather fascinating Global Disease Alert map that shows where cases of various infectious diseases are happening. It is color coded based on recency, the number of disease outbreaks, and the number of sources providing information for a location. You can filter the data by type of disease, if, for example, you just want to track out swine flu cases.
6. 
Brave New Waves – AntennaSearch is the Google Maps mashup that will tell you where all the cell phone antenna towers near your address (in the U.S.) are. If you are paranoid about radiation and brain damage, check this before buying a house in that nice neighborhood. Or if you’re just wondering how good the coverage might be.
7. Wikipedians – WikipediaVision Somebody in Bandung, Indonesia just edited the Wikipedia entry for the list of characters of Sabrina the Teenage Witch! Hold the phone! Waste a few minutes watching in real time as people around the world edit Wikipedia. Or not.
8. 
Twitterpedians – Not to be outdone, Twitter fans can check out Twittervision and watch a global map pointing out that some guy in Boston is eating a grilled cheese sandwhich or a woman in Sao Paulo just retweeted a link to a Tunisian rela estate site. Bonus points for the pictures that pop up in the lower left corner when someone tweets a twitpic link.
9. Nuke ‘Em Ground Zero is a java applet using Google Maps that simulates the thermal damage that would be caused to an area by a nuclear detonation. You can take your pick of several classic bombs, including the 15 Kiloton “Little Boy”, the 50 Megaton “Tsar Bomba” and even an asteroid (which pretty much dwarfs them all and obliterates a huge portion of whatever continent you’re on.
10. Is it Far? DistanceFromTo.net is a simple distance measurement between two points. How far are you from New York City right now?
11. Taxman – Business Planet lets you visualize which countries have the best and worst tax climates for doing business in. Qatar, Maldives, Hong Kong and Singapore seem to all have relatively low tax rates, according to this mashup.
12. Brew – The Beer Mapping Project points out the locations of breweries and brew-pubs in 12 different countries.
13. Nightlight – Nightime overlays NASA images of the Earth at night to show how urban areas are lit up at night.
14. Global Photos – One of the best mashups of Flickr and Google Maps is Earth Album. Clicking on an area of the map, or typing in a city in the site’s search function brings up a horizontal bar with a series of Flickr thumbnail images tagged to that place name. Clicking on the image will bring up a larger format of it, as well as any text description associated with that image. It is faster and simpler than most of the other mashups of this ilk. There is also a Cooliris version, that shows the thumbnails in a 3D wall. I think the photos selected are also filtered for interestingness; they are all pretty amazing.
15. – Get a Job – Job Maps is a search engine that pinpoints where your next job might be if you like to move around. Type in your job title, keyword or city, and it pulls in job results from the Indeed job search, overlaid on a map.
Have you found any other really cool Maps mashups? Leave your favs in the comments.