The entire idDevNet website downloaded html files with images just in case it ever goes down.
Ever been to idDevNet recently? Thankfully the site is still up and running for Doom 3. But you'll notice the quake 4 section is bone dry. It would be terrible if the Doom3 side were to disappear. This zip file contains all the web pages from the Doom 3 side of the site and images for each page... just in case that ever happens.