1. An information retrieval system comprising, embodied in one or more non-transitory machine accessible storage media: an electronic content and interaction analyzer module to cause one or more computing devices to generate user-specific semantic information for a plurality of pieces of stored content and interactions data; a query developer module to cause the one or more computing devices to: with the user-specific semantic information, interpret a search request; and based on the interpretation of the search request, develop a search query reflecting the user-specific semantic information; and a query executer module to cause the one or more computing devices to: execute the search query to obtain query results; and output a representation of the query results to an output device of the one or more computing devices; wherein the electronic content and interaction analyzer module is to extract a plurality of instances of a word from the stored content and interactions data, associate different user-specific semantic information with different instances of the extracted word, and store data indicative of the associations of different user-specific semantic information with different instances of the extracted word in a user-specific model, and wherein the query developer module is to interface with the user-specific model to develop the search query.
7. The information retrieval system of claim 1 , wherein the electronic content and interaction analyzer module is to associate different content or activity types with different pieces of the stored content or interactions data and store data indicative of the associations of different content or activity types with different pieces of the stored content or interactions data in a user-specific model, and wherein the query developer module is to interface with the user-specific model to develop the search query.