I just open-sourced some code I put together for tracking disaster relief efforts for Hurricane Sandy at https://code.google.com/p/sandy-disaster-recovery. Since I put it together rather quickly, it's very much targeted at events with flooding and high winds. I'd like to find some time (or help) in generalizing the software more. It's currently being used by a few dozen organizations in the north-eastern United States to organize work at the homes of a few thousand people who have been affected by the hurricane.
I'm not a web developer, but I had some fun using App Engine for Python 2.7, Google Closure, and the Maps API to put this together. I may put together a post later about tricks I found for getting high performance out of App Engine applications.
Feel free to poke around in the code, fork it, or use it yourself -- it's available under the Apache 2.0 license.