9. A system comprising a processing unit, one or more input devices, and a display, the processing unit being configured to implement a graphical user interface by processing user input provided via the input device(s) and by rendering images to the display, the graphical user interface enabling a user to associate each of a plurality of data items with any one of a plurality of clusters in a system-assisted manner and comprising: a visual representation of each of the data items; a visual representation of each of the clusters; means for enabling the user to selectively associate each data item representation with any one of the cluster representations; and means for outputting a user-perceivable indication that a particular data item representation should be associated with a particular cluster representation based on a system-generated recommendation.
9. A system comprising a processing unit, one or more input devices, and a display, the processing unit being configured to implement a graphical user interface by processing user input provided via the input device(s) and by rendering images to the display, the graphical user interface enabling a user to associate each of a plurality of data items with any one of a plurality of clusters in a system-assisted manner and comprising: a visual representation of each of the data items; a visual representation of each of the clusters; means for enabling the user to selectively associate each data item representation with any one of the cluster representations; and means for outputting a user-perceivable indication that a particular data item representation should be associated with a particular cluster representation based on a system-generated recommendation. 16. The system of claim 9 , wherein the graphical user interface further comprises: a visual representation of a group of data items that the user has determined should not be associated with any cluster representation; and a means for enabling the user to associate any of the data item representations with the visual representation of the group.