PROVIDING ONLINE TRADING SERVICES VIA A GLOBAL COMPUTER NETWORK, NAMELY, AN INTERACTIVE WEBSITE FEATURING A CENTRALIZED MARKET IN WHICH PARTICIPANTS SUBMIT ORDERS TO BUY AND SELL ACCESS TO BROADCAST TELEVISION VIEWERS, CABLE TELEVISION VIEWERS, DIRECT BROADCAST SATELLITE VIEWERS, RADIO LISTENERS, GLOBAL COMPUTER NETWORK USERS, AND READERS OF NEWSPAPERS OR PERIODICALS, WHO ARE ATTRACTED TO A PARTICULAR MEDIUM, WHERE A SET OF MATHEMATICAL ALGORITHMS IDENTIFIES THE SET OF APPROPRIATE TRADERS AND THE PRICES AT WHICH THE TRADES ARE EXECUTED