1. A method comprising: analyzing contents of a plurality of documents to identify, for each document, document elements and their respective placements within the document; ascertaining topics of at least some of the document elements based on keyword occurrences in the respective document elements; in an electronic data repository, storing individually addressable database entries for the identified document elements, each database entry comprising a unique document-element identifier, and storing the ascertained topics in association with the respective document elements; and using one or more computer processors, tracking, at sub-document level, user interactions with the document elements and storing, for each of the interactions, at least the document-element identifier of the document element interacted with and an identifier of the interacting user; and determining, for each of at least some of the interacting users, at least one of an interest or a field of expertise based at least in part on the tracked user interactions of that user and the topics associated with the interacted-with document elements, and for at least one of the interacting users, recommending at least one of content or another user to the interacting user based on the determined field of interest or expertise.