Hiya Dan ---

The only surefire way I have found to manage project scope is to document, document, document before a single line of code is written and have the client sign off on those documents. What is the minimum documentation? You should have the following:

Process Flow Diagram -or- Use Case Diagram
Entity Relationship Diagram -or- Data/Domain Model
Service Model (use Visual Modeller or other UML tool)

If there is a "feature" in the new system, it should be mapped on one of those three diagrams...if not, it's an enhancment. If you have to deviate from the models (very common), then you have to recognize that it's probably your fault.

On top of this, institute a formal "Change Order" procedure where key users in the project request a change, you add a quote and impact assessment to it, and the user(s) have to sign-off.

Sounds anal, but it's the only way to avoid problems once you're in gear.