Use Case Diagram

Below is the basic Use Case Diagram for the momsinmadison.com shopping cart. The purpose of the cart is to provide a mechanism for partners to purchase ad placements initially, and eventually, business directory listings and more. Because of the nature of the "product", there will be an approval mechanism between the partner initiating the purchase and completing the transaction.

A Use Case Diagram is an important artifact to create, if only because it serves to communicate with your client/customer/manager what "The System" consists of. In the diagram below, the system being developed is outlined in the light grey box. Once consensus has been achieved on this point, the high-risk use case(s) should be detailed out. The Use Case Model consists of your Use Case Specifications and a Use Case Diagram.

For a diagram like the one below, you can use whatever software or pencil & notepad that fits your budget - I use OmniGraffle from The Omni Group with a UML 2.0 stencil pack.