UC Davis Home Orcharding - A great place to start learning about fruit trees
Integrated Pest Management (IPM) - Information for a wide range of crops including fruit trees
Sacramento County Master Gardeners - Good information specific to growing fruit in Sacramento
Dave Wilson Nursery - One of the largest fruit tree nurseries in California.  They also provide great information and resources to help have a successful fruit tree growing experience.
California Rare Fruit Growers - Use the CRFG Local Chapters tab to find your chapter

Fowler Nurseries - This nursery located in Newcastle has varieties that will do well in Sacramento Valley.  They are also an excellent resource to answer your questions about fruit trees.
Trees of Antiquity - A great nursery located in Paso Robles that has a wonderful selection of rare fruit tree varieities
Peaceful Valley Farm Supply - A great source all kinds of farming and gardening supplies, including fruit trees and helpful tips and instructional videos
Fruit Tree Planting Foundation - “How to” resources and also many grant programs to support fruit tree planting

Growing Citrus in Sacramento (PDF) - UC Cooperative Extension of Sacramento County  

Fruit Tree and Vine Care Calendar (PDF) - UC Cooperative Extension of Santa Clara County 

What is Backyard Orchard Culture (PDF) - Dave Wilson Nursery

Tree Planting Recommendations (PDF) - Dave Wilson Nursery

Rootstock Information

Recommended Reading

How to Grow More Vegetables Than You Ever Thought Possible on Less Land Than You Can Imagine, by John Jeavons

The New Organic Grower, by Eliot Coleman

The Backyard Orchardist: A Complete Guide to Growing Fruit Trees in the Home Garden, by Stella Otto
The Apple Grower: A Guide for the Organic Orchardist, by Michael Phillips