17. One or more device-readable storage media with device-executable instructions that, when executed by a computing system, direct the computing system to perform steps comprising: storing, at a memory, a graphical structure comprising a first node representing a person, and a second node representing a document in the document repository, the nodes being connected by an edge according to automatically observed interactions between the represented person and the represented document, at least one of the nodes having an annotation denoting a topic, the interaction based at least in part on at least one of: a consumption activity by the person represented by the first node of the document represented by the second node, or a relationship between the person represented by the first node, and a second person represented by a third node; computing, at a processor, distances between two nodes of the graphical structure; receiving an identifier of a user who is represented by the first node; and automatically identifying one or more documents from the document repository, or people from the graphical structure, by using the identifier and using the computed distances between the two nodes.
17. One or more device-readable storage media with device-executable instructions that, when executed by a computing system, direct the computing system to perform steps comprising: storing, at a memory, a graphical structure comprising a first node representing a person, and a second node representing a document in the document repository, the nodes being connected by an edge according to automatically observed interactions between the represented person and the represented document, at least one of the nodes having an annotation denoting a topic, the interaction based at least in part on at least one of: a consumption activity by the person represented by the first node of the document represented by the second node, or a relationship between the person represented by the first node, and a second person represented by a third node; computing, at a processor, distances between two nodes of the graphical structure; receiving an identifier of a user who is represented by the first node; and automatically identifying one or more documents from the document repository, or people from the graphical structure, by using the identifier and using the computed distances between the two nodes. 18. The one or more device-readable storage media of claim 17 with device-executable instructions that, when executed by a computing system, direct the computing system to perform steps comprising storing the graphical structure with an annotation including a word that does not occur in the text of the document represented by the second node.