Alexandria Digital Library (ADL)
ADL contains more than 15,000 holdings, such as maps, images, and datasets, that are available online for public download over the Internet. The items currently cataloged in ADL are a portion of the holdings of the UCSB's Map and Imagery Laboratory. ADL offers a "Quick Placename Search", or a more detailed "Catalog Search" where you can search by specific collection, geographic region, time period, object type, object format, or keyword.
American FactFinder can be used to find statistics abut population housing, industry, and business. You can create reference maps and quick thematic maps, and search for specific U.S. Census data.
David Rumsey Collection - Historical Maps
The collection focuses on 18th and 19th century North and South American cartographic materials. The collection includes atlases, globes, school geographies, maritime charts, and a variety of separate maps including pocket, wall, children's and manuscript maps. The collection is searchable by country, state/province, publication author, keywords, or data field.
Digital Chart of the World - Penn State University
The Digital Chart of the World is an Environmental Systems Research Institute, Inc. (ESRI) product originally developed for the U.S. Defense Mapping Agency (DMA). The DMA data source is from the Operational Navigation Chart (ONC) series which have a scale of 1:1,000,000. Boundaries and layers of different countries are downloadable in ArcInfo format but are readable in ArcView as well.
Earth and Moon Viewer
The Earth and Moon Viewer shows images of the day and night regions of the Earth and Moon at this moment. It also includes images abouve any location specified by latitude, longitude, and altitude, from a satellite in Earth orbit. Moon images also show lunar surface formations.
So far this is what I've found... It's really just a discussion board for land surveyors, but several of the links that they have posted worked. Hope this helps.
Geographic Names Information System (GNIS)
GNIS contains information about almost 2 million physical and cultural geographic features in the United States. References are made to a feature's location by state, county, and geographic coordinates.
GEOnet Names Server (GNS)
GNS provides access to the National Geospatial-Intelligence Agency's (NGA) and the U.S. Board on Geographic Names' (US BGN) database of foreign geographic feature names.
Map & Imagery Laboratory (UCSB)
MIL's collections of maps, aerial photography, satellite imagery and other spatial data exceed 5 million information objects. One of the newest items listed is the Air Photo Indexes by County.
MapQuest gives you driving directions for U.S. destinations either city to city or door to door for the places and addresses you specify. It also has maps shoing streets in the U.S., locations of places in many countries of the world, city guides for a number of U.S. cities, and links to real-time traffic reports for some major U.S. cities.
National Atlas of the United States
The National Atlas offers maps, digital, geospatial and geostatistical data sets, and the capability for interactive selection and display of map layers. It updates the large bound collection of paper maps that was published in 1970.
National Geographic - MapMachine
The National Geographic MapMachine offers maps, country profiles and facts, as well as the ability to plan your next outdoor adventure with their trail maps.
Perry-Castañeda Library - University of Texas
The Perry-Castañeda Library offers public domain electronic maps to view or print. Maps are sorted into the following categories: World, Africa, Americas, Asia, Australia/Pacific, Europe, Middle East, Polar/Oceans, Russia/Republics, U.S., Texas, Historical, Thematic. There are also links to other map sites.
Southern California Earthquake Data Center (SCEDC)
SCEDC offers information and maps of recent earthquakes in California and Nevada, searchable earthquake archive (catalog), clickable fault map of Southern California, and information on historic earthquakes in Southern California.
U.S. Census Bureau Maps and Cartographic Resources
The U.S. Census Bureau offers links to publicly available printed and free, downloadable maps in pdf format. It also provides access to generalized, digital files suitable for use with a GIS, as well as links to two mapping applications derived from Census Bureau base map data.
U.S. Geological Survey (USGS)
USGS is a science organization dedicated to the timely, relevant, and impartial study of the landscape, our natural resources, and the natural hazards that threaten us.