This site links to various dataset across the federal government.
www.Data.gov -- repository for data and geodata from across the federal government, searchable by agency, data type, keyword, among others. Many, but not all Commerce data sets reside here.
Data.gov Commerce Data and tools can be found at
Data
http://www.data.gov/list/agency/1/0/catalog/raw/page/1/count/50
Tools
http://www.data.gov/list/agency/1/0/catalog/tools/page/1/count/50
Census Data – Population, household, housing, demographics. Economic census and monthly indicators, foreign trade, employment statistics, maps, geographic data and more. http://www.census.gov/
http://www.census.gov/main/www/access.html
List of Open Data Sites Around the World: http://www.data.gov/opendatasites
Amazon Listing of Public Data Sets: http://aws.amazon.com/datasets
Washington DC: http://data.octo.dc.gov
New York: http://nyc.gov/data
San Francisco: http://datasf.org/
U.K.: http://data.gov.uk/
http://www.cs.cmu.edu/~awm/10701/project/data.html
