Google Cache is a neat solution, when a web site that you want to browse is not avilable, if you're visiting a site and it returns a 404 error message, you can either do a search on Google for the site by prefixing the cache: operator parameters to your search query, that then becomes cache:www.google.com, or you can use ErrorZilla Firefox extension that provides a custom error page.
Google Cache outputs the page, from when —Google last crawled it successfully, so it may be outdated. Google doesn't store images, scripts and other embedded objects, but it tries to retrieve them from their original location, so most of the resources won't be accessible. In this case, you can click on the "cached text" link to see only the text. You can also add &strip=1 at the end of the URL or install Greasemonkey script that adds a link to the text version of the cached page in the search results page.
While reading the page, you may find other interesting links from the same site. Instead of repeating the same steps, you can install a Greasemonkey script that adds a new link to the Google Cache version for all the links from that page. This way, you can browse the web from Google Cache.