The Internet Archive’s WayBack Machine allows users to search for web pages that are no longer online. According to the Internet Archive, "the average lifespan of a web page is 44 -75 days," making it that much more important to preserve the designs and styles of our Internet past.
The WayBack Machine actually saves working versions of millions of sites and billions of pages (85 billion as of June 2008), an amazing resource for designers looking to see the look of the internet, and specific sites, going back as far as 1996.
To use the WayBack Machine, simply type a URL in the search field, and you are given a list of approximate dates that the archive has stored pages from. Choose a date and view a saved version of the site. While you will often come across broken links and images, this does not take away from the value of the service, as this huge archive of old web pages is a great research tool.