Paint / Coat roof to reflect sun's energy?

Just wanting to let everyone know:

So far, I've  put on one 6 gal. of the coating, and it covered about 1/3 of the roof.  It should have covered more, but it was a learning process finding the best way to mix it, spread it, etc.  I don't think we've had a particularly mild June, but the electric bill this month was lower than in June of '07 and '06 (when I started keeping track).  I have another 5 gal. that I've already purchaed, but it got too rainy to put on.  I'll be putting that on this Sunday (if it doesn't RAIN!!), and that should coat another 1/3 or more of the south-facing roof.  That will be 2/3 to 3/4 of the south-facing roof that will be coated before the next electric bill.  August and February are our highest electric months, since our home is all-electric.  Hopefully, I'll get the whole south-facing roof coated before August, and I'll post final results once it's done.

cliff notes: not even the whole roof is coated, but it already seems to help the A/C usage to have a reflective aluminized roof coating!