1. A method comprising: parsing, in a computer, an original search query received from a user over a network through a query web page to obtain at least one query term; retrieving a plurality of keywords from a database related contextually to a category of said query web page and said at least one query term; generating, in a computer, a set of modified queries, each modified query comprising said at least one query term and at least one keyword of said plurality of keywords; retrieving, in a computer, a plurality of advertising offers for each modified query and for said original query; removing, in a computer, any advertising offer that is not related contextually to said category of said query web page; and ranking, in a computer, the advertising offers not removed based on at least one predetermined parameter.