One of my customers is trying to create an interactive "matrix" of interdependencies for the various applications used in their company (it's a travel&leisure company with around 2500 employees).

The idea (still at the prototype stage) is to create a sort of Map, based on Visio or similar tool, which traces the communication and interdependencies between all the IT assets in the company, so that when someone asks for a change they can get an overview of the impacts.

This was mentioned in a casual setting and it will not be my responsability to directly work on this, but I did contribute the little I know already in terms of vaguely related methodologies (Zachman Framework).

I'd like to hear from the people in here if they know of methodologies, or tools, that may help this kind of effort, and if they have any specific experience to contribute. I'll digest the answers and send the result back to my customer, hoping this may be of some help with their task (which I consider a bit visionary and prone to all the pitfalls of any documentation project, but still well worth pursuing).