The Mercator Puzzle is an excellent way to visualize the distortions inherent in the Mercator projection, which conserves angles (useful for navigation) by exaggerating size at the poles (problematic in virtually every other use). Click and drag the countries in this in-browser app to see just how dramatically larger or smaller they become as you move them closer to and further away from the poles. [Boing Boing]

Previously: Review: Rhumb Lines and Map Wars; Reversing the Mercator Effect.