Free Sky Maps - Cities around the World: http://space.about.com/od/skymaps/a/skymapcities.htm
Click on a city to see the star map for that day.
Mag-7 Star Atlas Project http://www.cloudynights.com/item.php?item_id=1052
20 primary charts and one supplemental chart.
Surf Your Watershed http://cfpub1.epa.gov/surf/locate/index.cfm (Environmental Protection Agency)
You may enter a zip code or select a state and click on an area of the state to find the watershed for that area.
GISDATA Map Studio http://gisdata.usgs.net/ (US Geologic Survey (USGS) and Earth Resources Observation & Science (EROS))
"Our goal is to introduce seamless browse and delivery of the National Elevation Dataset, the National Land Cover Dataset, and the National Hydrography Dataset."
MetaCarta GeoIntel for Petroleum http://geointel.metacarta.com/
Indexes maps related to the energy industry. Users may enter a topic and location. [lots of journal articles related to the energy industry]