1. A computer system for use by a user, the computer system having a graphical display device, where the user is capable of accessing a collection of objects, the computer system comprising: an icon, stored in a memory of the computer system, the icon associated with one or more of the objects in the collection, and having a plurality of visual features that are controlled according to respective corresponding ones of a plurality of attributes of the object, wherein a first one of the visual features is controlled at least in part responsive to group memberships of other users who have accessed the object.