Sure, fans and using windows smartly can help a lot, but also check out these tips for when you really get desperate.
air conditioning

How to Keep Cool Without A/C

http://www.coolgreengadgets.com/2008/01/06/solar-powered-ac-is-genius/
One of the biggest Money and energy wasters finally got solar!SolCool Millenia has developed an ingenious air conditioner that uses solar power to power the A/C.The sunnier (or hotter) it gets, the more cooling power it has…thus, when the sun rises you have more cooling power . But just in case, the SolCool Millenia A/C is equipped with a 24 hour battery for those needing it at night.

Air Force Base Dyed Green
The largest employer in Abilene, Texas - and a model among military installations around the country - has reduced both its energy and water usage with various enviro-friendly approaches. By using graywater, Dyess Air Force Base has cut the city's water usage by 2 percent. With the installation of skylights, dimmer switches and by just turning off the AC, the base has reduced its electrical consumption by about 20 percent.

Auto air conditioning - greenhouse villian a white knight?
As of Jan. 1, 2011, air-conditioning systems for all new European-made vehicles must begin the switch to a refrigerant other than the current formulation, known as R134a - a mix that has 1410 times the global warming potential of carbon dioxide.