TheEconomist has used McDonalds most famous product to compile a "BigMacIndex" of international purchasing power.  http://www.economist.com/

''Since introduced, this index has often given good forewarning of over-/undervalued currencies, especially in "developed" countries.''

----

Additionally, I've found through my sundry travels around the world that the price of a value meal at Mc''''''Donalds is a great cost-of-living indicator for that country. To wit: In England, a value meal costs approximately 4 times what it costs in Canada.
-----
CategoryEconomics