Disaster Charter

Disaster Charter was a new find towards the end of 2012
The International Charter aims at providing a unified system of space data acquisition and delivery to those affected by natural or man-made disasters through Authorized Users. Each member agency has committed resources to support the provisions of the Charter and thus is helping to mitigate the effects of disasters on human life and property

It includes a useful interactive map mashup which allows visitors to search for particular types of hazards.

There's also a very useful Twitter feed to subscribe to if you want to keep up to date..
This recently added some excellent maps showing the extent of land that was flooded along the Thames and the Severn.