The viewpoint from which I've approached this project is that of Shlaer-Mellor OOA. Some people would categorise this as clunky ("based on database theory"), but for me my first encounter with OOA was an "aha!" moment.
You'll find much more on the OOA approach at the BridgePoint (was Project Technology) and Abstract Solutions (was Kennedy-Carter) sites. For the moment, though, the important points are:
You can see a set of Use Cases, written basically from the viewpoint of the Analyst actor. [I've just been on a Use Case workshop; I don't think these are really Use Cases. Still, you may find them helpful.]