"Sozai" is a Japanese term that basically describes images to decorate your webpage with. This is a great website to learn more about sozai images and explore different types of deco styles!
If you want to make your own images, I moved those links to the Image Help links page.
Any links under the Archived label is located on archive.org. You might be able to find more images and stuff if you change the snapshot date at the top of the page. Background (Premade) Background Tiles Pattern Cooler The Pattern Library Plaid Backgrounds