I'm not a big fan of AC. It's not an ideological thing for me (although it's hard for me to not be aware of how much energy those systems draw). Instead, it's mostly about comfort. Air conditioned spaces usually feel too cold to me, and too stuffed up. I'd prefer to have the fresh air and the open windows. Of course, there are some days when that's not exactly comfortable, either. Treehugger has a slideshow that can help. It's filled with tips for changing your lifestyle and your home to make things more comfortable at higher temperatures, reducing the number of days when you actually need the AC. This isn't all stuff you can do in a day — for instance, it will take a while to get a good shade tree outside your house — but the suggestions are interesting, and helpful, and most of them are focused cheap and simple, rather than high-tech and costly.