Cheapest ways to beat the heat

The cheapest way to beat the heat is to not let it in your home in the first place. 

1. Use blinds and/or curtains to block out the sun wherever possible, especially in south or west facing windows. Assuming you have window coverings already, cost of this is $0. If you miss the sunbeams, go outside!
2. Install retractable awnings. We put one over our front, west-facing window and it has made an enormous difference. If you're willing to do the installation yourself, you can pick up manual retractable awnings at Home Depot or Rona for around $200-$300.
3. For about $150 you can get an energy audit and find out where you can save more -- often you can adjust the insulation in your attic or roof to find savings year-round.
4. Don't use the oven to cook meals -- use a bbq outside, or a smaller appliance like an electric frying pan in the kitchen or just eat cold foods.
5. Similarly, turn off home electronics that kick out heat especially computers, televisions, DVD players, PVRs and game systems.

If you can't make any other changes and closing the curtains isn't helping, what else can you do?

1. Opening windows may or may not help, depending on whether you can get a breeze, although investing in a small air conditioner or window fan that can draw hot air out of your home may be worth it. (Cost $30 - $200)
2. You can always look to Lifehacker and similar websites to find plans for building your own DIY a/c.
3. Keep yourself cool. Drink plenty of water, have a cold shower, go to an air conditioned mall or similar to recover. Your home may not be cooler but you can keep yourself from going squirrelly!