Many state and local governments as well as utility companies offer incentives for energy efficiency and use of renewable or green energy sources...
In the past, the hard part has been finding these programs, as there wasn't a consolidated area with pointers to which programs were offered. North Carolina State University, together with the Interstate Renewable Energy Council and the North Carolina Solar Center, have created a huge database of incentives. This database is called "The Database of State Incentives for Renewables and Efficiency" or DSIRE.
The database is organized by state, allowing you to quickly see what programs are available in your area. The database shows energy incentives that range from incentives that discount your electric bill, to rebates on energy-efficient appliances, and even loans for items like solar panels. There's a ton of resources for every area, with over 50 programs listed for Texas, more than that for California, and something for every state.
See the database at dsireuse.org