1. A computer-implemented system for populating clusters of documents, comprising: a presentation module to place a set of clusters in a display in relation to a common origin; a document selection module to select one of a plurality of unclustered documents in the display and to determine an angle θ of the document from the common origin; a cluster placement module to compute for each cluster, an angle σ of the cluster relative to the common origin; a placement calculation module to determine a difference between the document angle θ and one such cluster angle σ; a predetermined variance applied to the difference; and a clustering module to place the document into the cluster when the difference is less than the variance.