1. A method for identifying clusters in two-dimensional data comprising: generating a two-dimensional histogram characterized by a grid having an x-axis and a y-axis and a selected number of bins in the x-direction and a selected number of bins in the y-direction, said data comprising n pairs of points (x i, y i ), i&equals;1,...,n, said histogram comprising fewer bins than said points; determining a density estimate based on said bins; and identifying at least one cluster in said data, said at least one cluster comprising a plurality of points which satisfy a selected density criteria.