After encountering yet another 404 error, tired of manually copy-pasting URLs, I finally took a few seconds to make a bookmarklet to search archive.org for a backup.
The link will go and fetch the most recent version of the page which wasn’t 404’d. If you find that’s not generally sufficient, try this bookmarklet which gives you the full archive index:
Archive.org, for those not familiar, is a not for profit archive of the internet. It crawls the web, making backups in case stuff goes down, so that it won’t be lost forever. Sites can opt out of course, using the standard robots.txt mechanism.
I hope you find it useful.