Ecogeek has another really good article up, this time about solar water heaters.

Solar water heaters are low tech. Basically, they're black pipes on
panels. There's no nanotechnology, no monosilicon crystals, and no DC
to AC conversion. Just run a pipe to your roof, through the panel, and
then back into your house. In many parts of the US, solar water heaters
can provide more than 90% of a household's water. And in all but the
cloudiest climates, they can provide more than 30%.

[...]

So why haven't we done it? A few reasons. First, installation can
cost more than $5,000 dollars, especially in older houses. Second, new
home buyers apparently don't like to see solar water heaters disrupting
their "roof lines." But there's good news on both these fronts.

First, banks are looking for new kinds of loans in America. A loan
that would, in effect, pay for itself and be more or less default-free
could be very enticing. A ten-year loan on a solar water heater would,
in effect, be free for the home owner and risk-free for the bank.

I decided to see what it would cost me to install a solar water heater in my home if I went to the bank and asked them for a loan. Now, assuming the interest rate is at 8% and it cost $6,000 to get everything installed, here's what the monthly payments would look like:

• 3 years = $156.68
• 5 years = $101.38
• 7 years = $77.93
• 10 years = $60.66

All in all, that's not too bad. A five year loan with these numbers would run you at a little over $1200 per year. Now factor in the savings on your heating bill, and that number comes down even further. The added bonus, as Ecogeek pointed out, is that it adds resale value to your home, which right now is especially important.