1. A computer-implemented method for establishing a location-based leaderboard by a computer system, comprising: a) associating a location of a user of the computer system in a virtual world to a smallest sub-region of the virtual world with the computer system, wherein the virtual world is partitioned into a set of regions and sub-regions using a hierarchical spatial data structure, wherein the regions and sub-regions are arranged according to a hierarchy, each sub-region being encompassed by a higher-level sub-region or region, and two or more highest-level sub-regions being encompassed by a region created by the hierarchical spatial data structure; b) obtaining a rank of the user within a region or sub-region encompassing the smallest sub-region to which the user's location was assigned, wherein the rank is determined using one or more statistics associated with the user, wherein the size of the sub-regions or regions created by the hierarchical spatial data structure are established based on population density for the region or sub-region, and wherein a region or sub-region is subdivided if the population density of the region or sub-region is above a threshold.