RoofRay has a very cool solar power calculator that uses Google Maps to allow you to trace patterns for solar arrays and get an estimate on cost, output, savings and ROI.
First you enter your address and it pulls up a satellite view of your roof. You add in regions and select the roof angle:
After a few more steps you get an estimate of your monthly bill and savings. I just picked an average of $300 for our monthly electric bill, but you can also input in the actual monthly charges or kWh used (it also knows the average kWh rate based on your zip code):
Finally you get an estimate of cost and years to break even:
It is obviously not an inexpensive venture and you must also take into account that there is a good bit of additional electrical hardware that must be installed in your house- DC/AC inverter, transfer hardware, etc. However being solar efficient does immediately add to the equity in your house.
If being less dependant on 'the man' or reducing your carbon footprint are important to you then this may be a good idea. Personally I would wait another 3-5 years to see if the costs of solar panels start to drop due to increased demand and better technologies...