An API to provide customizable RSS feeds should be considered, to allow users to subscribe to specific thematic areas, geographic areas and so on. This way, if for example someone was interested in data on aquatic resources in the Chesapeake Bay, they could subscribe and apply filters by custom search terms, by geography of interest, thematic keywords and so on.
This could either provide notices via e-mail, or by RSS, et cetera. As an example, Google allows users to do a custom search (e.g. Google News search or Google Blog Search with a user-specified query) and then the search results page displays an RSS feed icon, which users can then load into their RSS feed reader, to get regular updates matching those search parameters.