11. A computer-implemented system for determining topical interest comprising: a non-transitory memory; and said system configured to: receive signal information for a user of a document, the information including at least one signal value representing the user's activity with or relationship to the document and a signal weight for each signal value; compute a normalized signal value for each of the at least one signal values; compute a document interest value based on a sum of products of each normalized signal value and the signal weight associated with each signal value for the user; receive topic information for the document, the information including at least one topic and a weight for each topic, where the topic relates to content of the document, and the weight represents a level of confidence that the topic is associated with the document; and generate an update to an interest signature value for the user of a first topic by adding a product of the computed document interest value for the user for the document and a weight of the first topic in the document.
11. A computer-implemented system for determining topical interest comprising: a non-transitory memory; and said system configured to: receive signal information for a user of a document, the information including at least one signal value representing the user's activity with or relationship to the document and a signal weight for each signal value; compute a normalized signal value for each of the at least one signal values; compute a document interest value based on a sum of products of each normalized signal value and the signal weight associated with each signal value for the user; receive topic information for the document, the information including at least one topic and a weight for each topic, where the topic relates to content of the document, and the weight represents a level of confidence that the topic is associated with the document; and generate an update to an interest signature value for the user of a first topic by adding a product of the computed document interest value for the user for the document and a weight of the first topic in the document. 15. The system of claim 11 , further configured to: store a plurality of interest signature values in a database; and retrieve and display one or more users from the database having a predetermined rank or interest signature value for a query topic in response to a request regarding the query topic.