computer program products , computer systems and related methods are provided which compare a url , title and / or content of an online site viewed by a user with a first index of keywords relating to a plurality of subject matter categories , to determine any subject matter categories to which the online site relates ; cross - reference any determined subject matter categories with a second index of alternative online sites categorised by subject matter , in order to determine any alternative online sites in the same or similar category ; and perform a variety of actions in response including displaying a determined alternative online site to the user .