1. In a computer network having a plurality of user sites, a method of weighting the relative importance of a plurality of data items stored in a database on a server computer comprising the steps of: receiving at said server computer a keyword from a user site; generating at said server computer a plurality of listings corresponding to said keyword, each listing also corresponding to one of said data items; transmitting from said server computer to one of said user sites said plurality of listings; detecting at said server computer which ones of said plurality of data items are selected by said user site, said user site being transmitted each selected one of said data items upon selection of said corresponding listing by said user site; and updating said database to weight said selected ones of said data items as relatively more important than unselected ones of said data items with respect to said keyword.