1. A computer system for providing user-controllable relevance ranking of search results from a query on a collection of items of information, comprising: a relevance determination module having a first input for receiving a set of search results of a current search from a query indicating items in the collection matching the query, a second input for receiving relevance factors input by a user through a graphical user interface, and a third input for receiving information about the items in the set of search results of the current search to which relevance factors are applied to determine a score for each of the items, and an output for providing an indication of the score indicative of relevance for each of the items in the set of search results; and a sorting module which receives the score associated with each item and an indication of the set of search results, and an output providing the user an indication of the items in the set of search results in an order ranked according to the relevance score of each item.