National Geospatial Data Clearinghouse

Using the data elements defined in the Content Standards for Digital Geospatial Metadata, governmental, non-profit, and commercial participants worldwide can make their collections of spatial information searchable and accessible on the Internet using free reference implementation software developed by the FGDC. Use this resource to locate data and map servers from around the Globe

http://www.fgdc.gov/clearinghouse/clearinghouse.html

or, Search http://clearinghouse1.fgdc.gov/