My first house in Michigan was built on a slab with hot water heat, so A/C would have been both expensive and time-consuming--running ducts, etc. So I bought a ceiling fan for every room in the house. Worked wonders.

The house I moved from in Indiana was a two-story, and I had a whole-house fan put it that vented into the attic. Again, it worked pretty well.

We have A/C now, but I find I can do with just a de-humidifier during the worst days. The wife...well, the A/C is a necessity as far as she's concerned.