The EPA has some really good material on this subject that you can find here.
From my experience with being a building inspector for several years, there are some requirements in the building code for new homes located in areas that have high radon levels. This includes placing plastic sheeting under the basement’s concrete floor to create a barrier. However, there seems to be basically two systems that can be installed to draw the radon out from under the home and release it to the atmosphere. I have put together a short powerpoint on this that you can find on slideshare here. We have had a few homes in our city install these systems although I have to admit I don’t see a lot of them installed.
Depending on where you live, some state agencies offer free radon testing kits (Illinois mails these out to citizens).