U.S. Food and Drug Administration (FDA)
http://www.fda.gov

Healthcare Distribution Management Association (HDMA)
http://www.healthcaredistribution.org

Center for Disease Control (CDC)
http://www.cdc.gov

List of Controlled Substances:
http://www.deadiversion.usdoj.gov/schedules/index.html

NDC Database:
http://www.fda.gov/cder/ndc/database

New Drugs:
http://www.accessdata.fda.gov/scripts/cder/drugsatfda

Drug Shortages:
http://www.fda.gov/cder/drug/shortages

FDA Orange Book Lookup:
http://www.fda.gov/cder/ob

Medicare
http://www.medicare.gov

Weight Conversions:
http://www.metric-conversions.org/weight-conversion.htm

Controlled Substance Ordering System
http://www.deaecom.gov