Andrea
Overland's Background Libraryan index of ALL different sites and pages on
the WWW that has some sort of graphics you can use when making your own pages
Animated Backgrounds
Here you can find some examples of animated backgrounds. Most of them are too annoying for actual use, but they prove the concept. Both Netscape and Microsoft Internet explorer now support animated GIFs as backgrounds. The simple requirement to animated GIFs to make them usable as backgrounds is that the GIFs should be designed to smoothly connect to their copies both vertically and horizontally (usual requirement for backgrounds) in every frame of the animation.
Backgrounds Colleciton found here free for the taking.
