1. A social network method of offering recommendations to a user of a mobile device, comprising steps of: obtaining mobile numbers from a contact list of the user stored in the mobile device of the user; identifying the mobile numbers from the user's contact list as those of friends of the user, in a friend network database; for each respective identified mobile number, identifying a type of mobile device associated with the respective identified mobile number, in the friend network database; recording in the database, in association with respective identified mobile numbers, identification of software applications downloaded to mobile devices of friends identified by the respective identified mobile numbers; and based on the friend network data, and responsive to at least one inquiry from the user, transmitting information regarding friends having a particular type of mobile device and information regarding friends who have downloaded a particular software application through a network to a terminal of the user.