Government:

US Customs and Border Protection
Federal Maritime Commission 
Office of the US Trade Representatives
Bureau of Industry and Security
Food and Drug Administration
Fish and Wildlife
Animal and Plant Heath Inspection Service (APHIS)
US Department of Agriculture

Reference:

Virginia Port Authority
MSN Maps
Map quest
National Weather Service
Embassies of the World
Global Edge
Travel Warnings and Consular Information

News:

Journal of Commerce
Shipping Digest

Business and Finance:

Dunn and Bradstreet
US Export Import Bank
Currency Conversions
Pacific Rate Exchange

Import Information:

Harmonized Tariff Schedule
Code of Federal Regulation

Export Information:

International Trade Administration
Census-Foreign Trade Statistics
International Chamber of Commerce
Schedule B Codes