Wind Power
It's free and it's abundant. Wind power is something to seriously consider if you are thinking of becoming self sufficient in energy. There are a number of options available to you.
You can get a commercial company to fit and install a large turbine. This can be expensive and can take years to pay it's self off. The technology is getting better and more efficient but most energy experts we spoke to would agree that for most people the cost to savings ratio isn't there yet.
Mini turbine kits are available for roof top mounting. It's important to realise that something like this will not be able to run your washing machine! At best you could use them to power lights in a garage or shed. Roof top mounting isn't the best idea though. Turbulence caused by surrounding buildings can cause havoc with the turbines operation and damage it. The turbines vibrations will also be transmitted to the roof. It's also difficult to get a decent and consistant wind speed in urban and suburban areas. It some cases it can even cost you money when the inverter takes up more power than the turbine is using.
Build your own
The third and most self sufficient option is to build your own. This is a big enough task and you will need to be pretty handy. Ideally you will have a suitable area where you can mount a tower and have access to a clean wind source. By clean I mean free from turbulence. You should test your proposed site to ensure you will get enough wind.
There's lots of information about this on the web and some great books. Of them all Hugh Pigot is the godfather of home made wind turbines. Based in Scoraig on the West coast of Scotland (Plenty of wind there!) Hugh has been building and writing about homemade turbines for years. He has number of books with detailed plans available. If you are serious about wind energy here's the place to start - www.scoraigwind.com