This fantastic link resolves one use case that we have with our current users.
The point is that this is our first project with MS-SharePoint 2010 and we still have to learn how to resolve non inmediate user problems.
Users are used to navigate on folders, and try that they look into 100.000 documents searching is not a real solution for them.
This article resolves this and the important thing is the team has understood that we just cannot wait to the customer say us what they want to have: we can know it before because we know how they are currently working.
With this easy solution we are answering to the expected user experience the client is asking.