An extension that provides website data beyond normal analytics.

I am thinking of an extension that would offer me data about a website such as: when was the website last updated, and where? When was a page first published?

I wanted this extension/data when I was on this site (http://magpowersystem.free.fr/Repulsine/Repulsine.html) at the bottom it says: "in construction" so i wondered how long ago that was written and if/when there have been updates to that site/page.