Aids in the task of checking whether a command defined in a document preamble is actually used somewhere in the document. If you use the package cmdtrack to the preamble of your document, all \newcommand and similar statements between that point and the beginning of the document will be marked for logging. At the end of the document a report of the command usage will be printed in the TeX log, for example: mdash was used on line 25; ndash was never used.

The author is Michael J. Downes.