In the past few years ESRI has pushed into the server model of processing and analysis. ArcGIS Server is aimed at enterprise level implementations and web based mapping projects.

This is an extremely powerful piece of software with infinite configuration posibilities. It can be used in larger organizations to manage spatial data and hand;es satellite/orthophoto imagery very well. It can be setup to distribute maps or data inside your organization via a browser or an ArcGIS program or over the web to mobile or standard web users. Very powerful, very expensive and very intensive to customize and get running but a good solution to many problems.  If you are a nonprofit or a group ESRI deems worthy you can apply under their advanced grants program to get this expensive software for very little cost. Just be prepared to show you know how to use it and that you have a plan for implementing it.