Use Test Code Track Requirement
Even we have some bug track software to track the requirement/feature to set of codebut it still hard to find which line of code reflect which piece of requirement/feature. With combination of concept of User Story and implementation of Machine Specfication (MSpec), it will be easier to describe requirment by CODE and then we can drill down to deep in codes from original requirement. Therefore it is easier to identify the place of bug and make system easier maintenance. In the other hand, it is possible to extract the requirement from test code which can make requirement itself easier maintenance.