Direct marketers are adding another weapon to their communication arsenal: the corporate Web site. However, most Web sites do a poor job of delivering compelling and relevant content to online visitors. Online interaction optimization technologies like recommendation engines, targeting tools, and testing platforms can remedy this problem. Given the relative youth of the vendors in this emerging category, marketers must carefully assess functional capabilities to separate hype from reality. To help, Forrester has identified four questions marketers must ask each vendor and has outlined what the responses really mean.