Cool off your house with this tip from my Dollar Saver ezine:

We live in Utah, which tends to get very hot in the summer.
The house we are currently living in has full sun coming in
the front windows in the afternoon. To cut down on our cooling
bill from our window air-conditioner, we bought emergency
Mylar blankets for $1.25 each. We cut them to fit each window
section and sprayed a little bit of water on the window before
spreading out the Mylar. The Mylar sticks great and can be
removed whenever needed. The Mylar reflects the heat out in
the summer and they are thin enough to allow us to still see
out.
Crystal in Utah