A recent ad for Haggar

Crispin Porter + Bogusky's deal with Haggar, in which the agency took an equity stake as part of its compensation, stands out as the rare exception. The usual is for agencies to sell their ideas based on the number of man-hours it took to prepare, rather than be compensated based the success of their solutions.

"The discussion is beginning to shift from 'What does it cost to generate work and services a client wants?' to 'What is the value of the services and materials the agency is creating for the client?"' Ronald Urbach, partner of Davis & Gilbert told AdAge. "Innovation is reaching a critical mass."

Like Crispin, New York-based Anomaly prices itself based "on the subjective theory of value." With client Virgin America, for example, the company will get a percentage of the revenue from the sales of an in-flight entertainment system it helped to design.

Looking back in time offers up a long lists of missed revenue opportunities. For example, Goodby, Silverstein benefited in no way from the millions in licensing fees and royalties that its 1993 "Got Milk?" campaign ultimately generated.