I've done it a lot; leave a comment, an edit, or maybe even start writing an answer on a post I saw on the front page.
Then I notice the post dates are from 2010; an ancient question someone edited or posted an answer to. It would be nice if after a few months or so a little icon or indication showed up on old posts on the "active" page.
MS Paint mockup go:
The icon could have a
title attribute, so when you hover your mouse it says something like:
Originally asked May 2010
It could save us some accidental necromancy, or even be a good indicator in Unanswered Questions/ect for an opportunity to get the Necromancery/Revival badges. It would also give an indication of when someone's been answering or editing a very old post, which reeks of intentional bumping or late answers.