Over the past year, a number of interactive marketing attribution offerings have emerged — giving marketers insight into their marketing ROI and allowing vendors to create a more entrenched relationship with their clients. But early movers, such as Atlas and ClearSaleing, come from various parts of the marketing landscape, meaning that their attribution offerings vary depending on legacy products, services, and client bases. Look for upstarts and industry leaders like DoubleClick and Omniture to join the market as soon as client demand increases.