RE: tracking numbers: quite useful, especially with date as part of the number, can also be adapted to increase confidentiality where sensitve materials are concerned. I am not too comfortable with a tracking number that does not have meaning but there are ways around that such as creating your own Dewey Decimal system.
RE: Pile-File:I think the analysis is brilliant. I need more time to digest its applicability to me. I think maybe I could use this to manage my Active Projects.