Detailing his quest to discover what makes a planet habitable; Sean Raymond of Bordeaux observatory utilizes a binary system, gas giants, leading and following trojans and binary planets in order to cram 60 potentially habitable worlds into the goldilocks zone.
http://planetplanet.net/2013/06/11/build-a-better-solar-system/Part 2 starts here:
http://planetplanet.net/2014/05/13/building-the-ultimate-solar-system/Does this absurdity remind anyone of aurora? :p
As an aside I read somewhere that it's possible that milky way holds at least 15-30 billion terrestrial planets...