USDA Complete Guide to Home Canning
The USDA Complete Guide to Home Canning provides very detailed instructions on preparing, processing, and storing home-canned foods. The main page is simply an index of text links; the actual pages are PDF files, which can be slow to download. However, the upside is that they are easy to print, and you can select just the items you plan to preserve.
Tool or Gardening Product
Villaware Victorio Food Strainer and Sauce Maker
A Victorio food strainer makes short work of preparing applesauce. You simply wash, quarter, and cook the apples until they're soft, ladle them into the strainer, turn the crank, and the strainer separates the fruit from the seeds and skin. I've canned 25 quarts of applesauce in an afternoon using a Victorio.