There are a number of resources available where you can begin to explore ideas for diversification. The following two sites will help you get started, but certainly you should also check with your state's department of agriculture and your local Cooperative Extension office to see if there are local programs that can help.
The National Sustainable Agriculture Information Service (also known as ATTRA) has a number of fact sheets available that may help you narrow down some of your options.
The Agricultural Marketing Resource Center has many resources available. You can learn about emerging market trends and value-added options. You can also sort the site by specific crops and commodities.