Today's Social Networking sites exert a much stronger pull on their members than more general sites, which makes the selective power of a Social Network potentially more useful to advertisers than broader behavioral targeting.

The sheer number of users and their passion for the topic is a major driving force that has yet to be fully understood or tapped. The consensus opinion of experts appears to be that, as long as advertisers respect a Social Network and try to integrate ads that enhance the underlying experience, and as long as they understand the reality that many of these people are not willing to leave their online community to visit advertisers' sites, they can benefit from adding Social Networks to their Behavioral Targeting programs, particularly when they go for brand building.

The goal should be to get people to take away with them a deeper appreciation for a brand, in recognition that they will ultimately respond better to other ads for that brand's products in other contexts.

"Overall," says Forrester's Kim, "the future is very bright, because Social Networks are segmented for special interest groups, and that hits at the essence of Behavioral Targeting. Considering such new factors as the ability to block pop ups and to dodge advertising with TiVo, it's clear that advertisers need to explore this and other new directions."