Performance-based marketing is quickly emerging as the ideal method of conducting business. Gradually, agencies have begun to recognize its benefits at a time when more and more advertisers demand proven, quantitative results. Across search and display media spends, paying for performance has proven itself an effective way of maximizing return on investment. As agencies and brands are now adding e-mail to their media spends, they are beginning to truly reap the benefits of an integrated, multimedia, performance-based spend.