It's called the Wayback Machine.
You type in the URL of a website that's gone 'belly up' and you can view a previously archived version of it. Which means you can find those fanfic sites that you used to know and love! LOL.
It appears you do need the URL, however! I tried several last night and it works like a charm. Quite cool. A chance to DL fic that you might have missed when you had the chance!
Plus it shows 'earlier' versions of existing sites, too. Interesting!
It didn't seem to work for the old 'official' Backstreet site, though. (The one I paid to belong to. Sigh.)
An aside: I wonder when in hell BSB will finally get the so-called 'new' official site up! I've been hearing about it for over a year now... (Not that you can beat fan sites, but still!)
Imagine the work and expense involved in archiving every site on the web. Whew!
Back to work!