Inventory and Accounting
This page describes a set of analysis patterns which are useful for modelling any situation in which accounting or money/time/resources is required. The basic principle is that events in the real world have to logged and accounted for in some way. However, this gets tricky when you consider that some events can be revoked / amended at a later date.
Martin Fowler writes extensively about this analysis pattern in http://www.martinfowler.com/apsupp/accounting.pdf, which is an updated version of Chapter 6 of Martin Fowler 1997. This page should be considered a summary of his work.