Lead generation is one of the largest, fastest growing segments of the online marketing industry, and the momentum will only increase in 2007.  Agencies are smarter, leads are better qualified and technology is more advanced than ever before.  Many trends will emerge in '07, but the real headliner will be the proliferation of the ping tree. The ping tree, which quietly gained prevalence in 2006, is a process that allows sellers to monetize every lead by shopping them to multiple buyers in real time.  In this tiered-pricing marketplace, sellers can release highly qualified leads at premium prices to buyers with stringent business rules, then approach other buyers who have more general criteria with remaining inventory at lower prices. This system benefits both sellers and buyers.  Sellers capitalize on premium pricing and a higher percentage of marketable leads, which, in turn, encourages affiliates to do more business with them. Buyers wh