Thanks for the hint, Devon.
I have been using several sources as I plan for permaculture plantings in eastern Quebec:
http://www.seeds.ca/en.php (Seeds of Diversity, Canadian seed preservation organization)
http://www.seeds.ca/rl/rl.php (List of Canadian seed companies selling heirloom seeds)
http://www.seeds.ca/sl/csci/ (Plant list, with catalog sources for each species)
http://www.lasocietedesplantes.com/ (French only; heirloom seeds for northern climates; plus, they are just down the road a ways from us!)
http://www.seedsavers.org/ (Seed Savers in Decorah, Iowa; heirloom seed exchange; I visited their farm a few years back -- fabulous place)