I made up the name obesochart, but found the chart in question in this news outlet. A few more, and other nice pics, are published in the same article.
They divided the total amount of real estate value (in dollars) by square mile, and then computed averages for each state. So the map below is about US, but the state areas are transformed (shrunk or inflated) to match their share of real estate worth, with California and New York being the biggest (most expensive) ones.
An interesting finding of their study is that the total value of Upper East Side homes (in Manhattan) is greater than that of several entire states.
Click here for other visualizations.
Nice term, but it is called a Cartogram (https://en.wikipedia.org/wiki/Cartogram) and has been for some time :-).
Here is a link to a tutorial for a tool that can allow you to build them - http://gis.yohman.com/blog/2011/11/07/tutorial-building-cartograms/
Personally, I prefer obesochart. :)
This one was made by me using Scapetoad, the same tool mentioned in that tutorial.
Cartograms have been around for a while, but it wasn't until recently that they could be generated algorithmically. I suppose that's why you don't see them around very often.