Ransom
-Help liberate over 56,000 digital USGS maps. Donate or purchase maps on DVD to meet the ransom demand. Once the $1600 ransom is met, all maps will be handed over to the Internet Archive. The Internet Archive will make every map available for free download forever!

Here are examples of different ways of projecting the Earth's surface and a brief discussion of the pros and cons of each of the methods.

List of data sets available from USUS. Huge and quite up to date.