A system for automatically keeping track of who is responding to a particular emergency and automatically creating a "contact list"/"phone book" of those that are there. See presentation by Andrej Verity - http://www.youtube.com/watch?v=ypA9Iza5OFg
Focus on simplicity and ease of use.
Contact information is name, email and phone number
Availability is Start Date to End Date (one stretch, no times, no complexity)
No worries on security for now (access given when link is received)
User ties themselves to one cluster (a cluster is an area of focus for humanitarian response)