1. A system for dynamically invoking a remote computational resource for a user operating a local computer system comprising: means for operating for the user a base application on said local computer system such that the computational resource is external to the base application; means for receiving into the base application a series of user interactions which establish a context; and means for in response to the series of user interactions dynamically instructing via a network, responsive to the context, the computational resource to perform selected computational operations; wherein the computational resource comprises a remote computing system having an information retrieval system.