Canadian Food Inspection Agency
http://www.cfia-acia.agr.ca
Government department responsible for inspection and control of agricultural goods entering Canada. Warnings and alerts are also posted here.

Customs Information for Exporters
http://www.exportsource.gc.ca
Good concise listings of export regulations, handbooks, forms and web links.

Dept. of Foreign Affairs & Int'l Trade
http://www.dfait-maeci.gc.ca
Look in the Trade Negotiations and Agreements for excellent information on Export and Import Controls including control lists and permits.

Importers Association
http://www.importers.ca
This association offers its members a wide range of import assistance and an opportunity to voice change in current regulations.

Revenue Canada Customs
http://www.rc.gc.ca/vco
Although this government site is in development, it provides forms and is an excellent source of tariff information.

Standard Council of CA - SCC.CA
http://www.scc.ca
This link provides product specific export advisories by email.

Statistics Canada
http://www.statcan.ca
A great site for Canadian demo-graphics, including import and export statistics.