This paper describes work being performed under a NASA Earth Science Technology Office grant to develop a modular Sensor Web architecture based on Open Geospatial Consortium (OGC) standards, which enables discovery and generic tasking capability for sensors, both space-based and insitu. A series of increasingly complex demonstrations have been developed to prototype this architecture. Recent demonstrations have made use of the Hyperion and Advanced Land Imager instruments on the Earth Observing 1 (EO-1) satellite, the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra and Aqua, the Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) on the Terra satellite and the Wildfire sensor on the Ikhana Unmanned Aerial System (UAS). This Sensor Web was used in the recent Southern California fires during October 2007 to deliver key wildfire imagery to the San Diego county Emergency Operations Center (EOC) to assist emergency workers with situational awareness. Presently the team is in the process of prototyping the use of this sensor web for floods in collaboration with the International Federations of the Red Cross/Red Crescent for better flood disaster management. The paper will also describe a general overview of the modular architecture that has thus far been built and capabilities still needed to realize the full vision.