IRIS is a consortium of over 100 US universities dedicated to the operation of science facilities for the acquisition, management, and distribution of seismological data. Includes the Seismic Monitor which allows you to monitor earthquakes in near real-time.
Includes features allowing you to search for volcanoes by region, name or eruption data. Also has a wonderful image gallery and provides access to volcanic activity reports that provide recent and historic information on volcanic activity.
The Geospatial Multi-Agency Coordination Group or GeoMAC, is an internet-based mapping application that allows users to access online maps of current fire locations and perimeters in the conterminous 48 States and Alaska.