Some interesting sites showing various financial incentives/tax breaks/laws concerning solar and wind power by U.S. state, as well as giving you a really good picture of what a solar energy system would really cost to incorporate on your home.
Database of State Incentives for Renewables & Efficiency
BP Solar / Home Depot - Overview of a residential system
PV Cost/Benefit Calculator
US Dept of Energy Wind & Hydropower Technologies Program
Wind Turbines/Farms Database