Wikimedia Bugzilla is closed!

It would be useful to have a tag, e.g. {{TIMESTAMP}} that translates to the
~~~~~ timestamp ONLY when a template is subst'ed. That way, when for instance a
"cleanup" template is substed, it would show the date it was placed on the page.
This is also useful for categorizing things by day or by month, e.g. "cleanups
placed in March 2005".

Alternatively, of course, we could employ a bot to change the template every
day/month.