Ventilation is simply a way to move air. Ducted Air Conditioning Systems take the warm air from a central location in your house, treats the air, and then sends air throughout the house.
Sometimes you just need to move the air to keep things cooler. Attic Fans and Whole house fans are one way to keep your house colder.
Attic Fans

Master Flow
500/750 CFM Low Profile Solar Powered Roof Mount Exhaust Fan

Remington Solar
20/25/30-watt Solar Powered Fan
1,280; 1,450; 1,550 CFM

Ventamatic
Cool Attic 1000 CFM Solar Powered Roof Attic Vent with Dome Mounted Panel
Whole House Fans

1000 CFM Insulated Roof or Wall Mount Whole House Fan

24 in. Belt Drive Whole House Fan with Shutter


Quite Cool
Classic CL-6400 Advanced Direct Drive Whole House Fan with Dampers