Clearly, much work needs to be done to address the diverse and sometimes unique on-line information needs of public health professionals and health policy analysts. In some cases, there are needs for complex new knowledge bases created via linkages among multiple databases (e.g., public health-relevant geographic information systems).
However, in many other cases, what is needed is a more systematic way of capturing the so-called grey literature: policy documents, government reports, legislative summaries, industry group publications, descriptions of best practices, and so on. In general, very little of this grey literature is formally peer reviewed, most is not available on-line, and almost none of it is accessible through such trusted databases as MEDLINE. Yet, it is frequently this practice-oriented literature that is of most importance to public health professionals and health policy analysts. New systems are needed to make this large and growing body of information accessible electronically in a well-indexed, timely, reasonably comprehensive, yet meaningfully filtered, manner. The development of such systems presents new and difficult challenges to those interested in ensuring on-line access to such information for health policy analysts and public health professionals.