Per-dataset "home pages" are needed. These should render the available metadata from the individual dataset repository (see #2), and probably also a map component that plots only the sites from this dataset. Other features could be considered, such as filtering/faceting automatically generated on the basis of the kind of metadata that individual datasets preserve but that aren't likely to be helpfully commensurable across datasets.
Per-dataset "home pages" are needed. These should render the available metadata from the individual dataset repository (see #2), and probably also a map component that plots only the sites from this dataset. Other features could be considered, such as filtering/faceting automatically generated on the basis of the kind of metadata that individual datasets preserve but that aren't likely to be helpfully commensurable across datasets.