Very good question! The general theme of web archiving is still not adequately addressed (imho), in order to fight bit rot of hyperlinks and preserve digital online web sources. I find it amusing that usually nobody seems to think about or care for "who conserves the web for future generations".
Coming from academia, I myself primarily use The Wayback Machine. In research literature I also encounter some use of WebCite (http://www.webcitation.org) in references.
Anyone interested in web archiving, might have a look at introduction to web archiving at wikipedia, including an overview of web archiving services: http://en.wikipedia.org/wiki/Web_archiving
If the past version of the page you are looking for is <3 months old, you could also try cache:URL in google search (or equivalent function in other search engine).
Coming from academia, I myself primarily use The Wayback Machine. In research literature I also encounter some use of WebCite (http://www.webcitation.org) in references.
Anyone interested in web archiving, might have a look at introduction to web archiving at wikipedia, including an overview of web archiving services: http://en.wikipedia.org/wiki/Web_archiving
If the past version of the page you are looking for is <3 months old, you could also try cache:URL in google search (or equivalent function in other search engine).