Simple and works as it should, add some options Rated 4 out of 5 stars
The archive.org button works as expected on pages that are down or have a different page not found message, and the page automatically loads an archived version of the page when '404 - Page Not Found' is in the title. All in all, a simple extension that does what it says.
However, I find it funny that visiting the extension page AMO triggers the loading of a page from archive.org due to the extension's name. Consider changing the name, as it's very distracting. If possible, make the automatic loading an option you can turn off, with possibly a whitelist so that false positives won't be loaded again. Thanks!
originally i left it as a simple test that extension works, but realized it can be confusing...