Wayback Machine

The  Wayback Machine  is a digital archive of web pages created by the Internet Archive. It allows you to look up past versions of a URL. It also allows you to submit a URL to be captured as it exists currently.

How To
Getting the oldest available version of a URL:

URL="http://example.com" wget -O- -q "http://web.archive.org/web/timemap/link/${URL}" | grep "first memento" | sed -r "s/^<([^>]+)>;.*$/\1/"