Find the coolest part of your house. If you have a basement (sorry, lowland and swamp dwellers) just stick it down there. You'll save several degrees over the rest if the house. Wrap it up in blankets our jackets our whatever so that temp swings have a lessened effect in the beer. Without adding any level of technology to the mix that's about all you can do.
Beyond that you can search this forum for "bucket in a bucket" or "swamp cooler" threads that'll show you the low tech temp control systems people have made by sitting their fermenter in a large bucket with sanitizer solution and rotating ice packs to drop the temp.
Really a stable temp is more important than hitting a certain temp range. You can find a yeast that will work well in almost any climate and a recipe that will fit that yeast. A lot of brewing is about making what fits your set up the best, and your climate has a big impact on it.
Hope this helps.
Edit: ninja'd