The 2011 NHS Atlas of Variation is out! And sure enough, it shows dramatic variation in healthcare utilization and in GP practice patterns around the UK. North Lancashire doctors, for example, prescribe 25 times as many pills for dementia as those in Kent. Only 3 of every 100,000 people in Devon and Cornwall are admitted to NHS care homes, while in Northumberland that number is 190. Peterborough has an angioplasty rate treble that of County Durham. Coverage here and here.
The US has regional practice variation which is just as dramatic; it's been documented for decades by the Dartmouth Atlas of Healthcare, whose creator, Jack Wennberg, is the father of regional-variation research.
NHS has a webpage collecting different countries' medical-variation atlases here.