Currency conversion is one of those abstract concepts that's often hard to truly conceptualize. Sure, I realized the dollar is weak, but while one of my UK friends was visiting the states, I had a difficult time understanding exactly how strong the pound or Euro was, and when attempting to translate it into a "real world" situation, pricing disparities between countries make it difficult still.

Now, an Australian securities firm takes that metric and standardizes it using one of the most pervasive devices of the moment, the iPod. Commonwealth Securities, Ltd. uses the two gigabyte version of Apple, Inc.'s (NASDAQ: AAPL) iPod Nano to measure wealth disparity across the globe, creating the iPod index.

In theory, my friend shouldn't be so excited to come to the U.S. and purchase an iPod for "cheap," but rather the iPod's price should equate around the globe, according to currency conversions. Of course, that's not the case. In fact, Brazilians pay the equivalent of $327 for the flash-based device, while our Canadian neighbors to the north pay a mere $144 for what costs us here in the U.S. $149.