1. A computer-implemented method of ranking document returned in a results list in response to a search query, comprising entering a search query; displaying a results list of documents returned in response to the search query; receiving and storing input from the user indicating the relevance to the user of a document in the results list of documents; modifying the weight of previous input from the user indicating the relevance of the document to the user; associating the user input indicating the relevance to the user of the document in the results list with the search query and with the document; determining a relevance formula having variables and parameters, the relevance formula for computing a relevance score for the document and the search query, wherein the variables comprise a plurality of features, a feature of the plurality of features comprises one of: a frequency of occurrence of a term in the document, a frequency of hyperlinks containing a term in the document, and a frequency of occurrence of a term in an abstract of the document, and the parameters comprise a plurality of weighting factors corresponding to each of the features; ranking the document based on the relevance score, wherein the relevance score is dependent on the user input associated with the document and the search query; and presenting the ranked results list of documents to the user.