I purchased a little tool online for really cheap, and you stick it into the soil, twist it 1/4 circle, and pull it out. It leaves nice aeration holes because it brings part of the dirt with it. Makes it easy to see if the container or in ground soil is too damp, too dry, or just right. It is called a soil sleuth. Google it.
Other than that there are fabric pots that air prune the roots, and appear to give great results. I'm looking at those too. Those are from smartpots.com. The testimonials have convinced me that these are the way to go.
As cheap as I am, I'm thinking about making my own smart pots with some landscape "weed cover type" fabric, a chicken wire form for support, and a staple gun! The concept there is the drainage through fabric is great, and when the roots hit the fabric wall, they don't circle. The air stops their growth, and they branch out and create more root mass where you want the roots to be, and thus make a larger nicer plant.
There are a few pots that are similar in concept to the smartpot, and here are some links:
http://www.rootmaker.com/products_containers.php#jump http://www.fanntum.com/pricing.htm
We do what we can to get the most from our plants! Good luck with yours!