Thematic Mapping has produced Earth Atlas, a prototype web application for viewing KML files with the Google Earth plugin.
Earth Atlas comes with links to many of Thematic Mapping's own KMLs. It is also possible to view any KML file in Earth Atlas by pasting the address into the 'Your KML' panel in the left hand sidebar or by adding the KML to theEath atlas URL, like in this example:
Earth Atlas' panel interface is very well designed. A left hand side panel displays the KML links and it can be collapsed to expand the Google Earth view. Additional information about the KML is displayed in a panel under the Google Earth view. This panel can also be collapsed.
Thematic mapping have released Earth Atlas under a GNU General Public License v3, so it is possible for other developers to create their own versions. This is exactly what Soren Johannessen has done.
Soren has created a Danish language version of Earth Atlas, which he is calling K2 Gaiaprojector.
Soren's K2 Gaiaprojector displays a number of Soren's own excellent KMLs about Denmark. The KMLs are arranged into a number of categories, such as culture, statistics and environment. Of course if you prefer you can also view all of the KMLs in Google Earth. The link for each KML is provided at the bottom of the screen.