Swamp cooler is about as simple as it gets. Although you could do the wet t-shirt/towel on the fermentor with a fan blowing on it. Search for that here on the forums. If you want precise temp control without using a fridge look into building the "son of a fermentation" chamber. I've got one that I do ales in and it works great. Added a STC-1000 temp control to it, which allows very precise temp control.