1. A computer program product comprising a non-transitory computer readable medium having a computer readable program stored therein, wherein the computer readable program, when executed on a computing device, causes the computing device to: receive a user input specifying an input arbitrarily hand-drawn shape tag, wherein the input arbitrarily hand-drawn shape tag is a non-text graphical symbol that is an annotation added to an existing electronic document by the user input; update a set of shape tag equivalence classes within the data processing system based on the received user input to assign the input arbitrarily hand-drawn shape tag to a shape tag equivalence class having similar previously entered arbitrarily hand-drawn shape tags; generate rankings of shape tags, in the shape tag equivalence classes, relative to one another; generate the shape tag cloud display based on the generated rankings, wherein a representation of shape tags in each shape tag equivalence class in the set of shape tag equivalence classes, within the shape tag cloud display, has display characteristics based on the generated rankings; associate, with each shape tag in the shape tag cloud display, a link to one or more electronic documents associated with the shape tag; output the shape tag cloud display; receive a selection of a shape tag in the shape tag cloud display; provide, in response to receiving the selection of the shape tag in the shape tag cloud display, a listing of the one or more electronic documents associated with the selected shape tag, wherein entries in the listing comprise a title of a corresponding electronic document and an associated degree of matching between the corresponding electronic document and a shape tag equivalence class corresponding to the selected shape tag; receive a selection of an entry in the listing of the one or more electronic documents to thereby select an electronic document from the listing; and provide in response to receiving the selection of the electronic document, an output of the selected electronic document.