Imagery

Earth's Current Temperatures
Land and sea temperatures for the entire globe.
http://www.ssec.wisc.edu/data/comp/latest_cmoll.gif

Global Climate Highlights
Major events and anomalies.
http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/GLOB_CLIM/current.html

Operational Significant Event Imagery
Produces high-resolution, detailed imagery of significant natural or anthropogenic environmental events which are visible in remotely-sensed data.
http://www.osei.noaa.gov/

StormVideo.com
Severe storm and tornado footage and video.
http://www.stormvideo.com/

US Weather Maps
Index of about 60 surface, upper air, temperature, and computer model maps from around North America.
http://cirrus.sprl.umich.edu/wxnet/maps.html

Weather and Climate Data
A variety of maps provided by the National Weather Service.
http://wxmaps.org

Weather Map Sites
The Perry-Castanela Library collection of weather map websites, provided by the University of Texas Library Online.
http://www.lib.utexas.edu/maps/map_sites/wea_sites.html

Window on the World
Satellite images, rainfall radar, lightning activity, forecasts, live webcam views from around the planet and links to other sites.
http://uk.geocities.com/pete_lean/