Seeds of Change is a USDA certified organic seed company based in New Mexico. A number of home gardeners & farmers have cited Seeds of Change as an excellent jumping off point to the world of seed catalogs.
I chatted up a few farmers recently at the end of season markets around Boston and was advised that looking at a variety of seed catalogs would give me a good idea about special or heirloom variety of veggies I may want to grow, but my best bet would be finding a reputable and well known seed company based in the same region that I am. If a reputable source in my area has success on their farms with varieties that I'm interested in, chances of my success go up due to similar (not the exact same) climates. The name which came up most often from the farmers was Johnny's Seeds of Winslow, ME. I won't be ordering all of my seeds from Johnny's but for starters a good number will be coming from them.