If you have a large organization good chance that you will have suppliers wanted to work with you to supply goods. So being able to register and keep track of these suppliers can be useful when you want to go and look for a new supplier for a specific category of products. This is a quick walkthrough of a supplier registering.
You will see in this example we allow Windows Live users to be able to sign in. This is managed through Azure ACS and requires some configuration of Azure ACS and SharePoint to support the claims authentication.