Outside of the nonsensical urban tesseract known as the West Village, Manhattan's street grid system is famously simple: Avenues run north/south(ish), streets run east/west. A phrase like "5th Avenue and 33rd Street" isn't just an arbitrary address, it's a cartesian coordinate that can actually help you get to where you're going as well as recognize when you've gotten there. With a system this easy, it's hard not to wish the whole world used it. Harold Cooper's brilliant Google Maps mashup, ExtendNY, gives you an idea of what such a world would look like: Punch in any address or location on the globe, and it tells you what its NYC-style address is.
For example: My apartment in Brooklyn is near the imaginary corner of S. 46th Street and East 15th Avenue. And 10 Downing Street, the official residence of the United Kingdom's Prime Minister, is located at the intersection of 63,709th Street and East 10,894th Avenue. McMurdo Station in Antarctica? No problem: It's on South 60,313th between 74,277th and 74,278th Ave. (Why does the grid curve, when you zoom out? Geometry: Cooper is compensating for the fact that the map is flat while the Earth is actually curved. Thus, any street on the block traces an arc across the Earth's surface--the true "straight" line that you'd get if you were walking precisely due west or north, etc.)
But before you think this is Cooper's interaction-design version of claiming New York as the center of the universe, try zooming into a depopulated area of eastern Uzbekistan on his map. Somewhere in there is the real center of the ExtendNY universe, where the grid system collapses in on itself like a black hole. (Hm, is there a Ray's Pizza on that block?)