Earthquake [ http://earthquakedb.com ]
Largest known earthquake database with statistics and information about locations, magnitudes, with google earth support, search engine and RSS feeds

Tsunami [ http://tsunami.name ]
Largest known tsunami database with statistics and information about locations, magnitudes, with google earth support, search engine and RSS feeds

Caldera Volcanoes [ http://volcanodb.com ]
Browse all the currently known volcanoes with map locations, times of eruptions and much more!