Dave has been musing on whether the web is spatial or not. I'm not sure that the web itself is, but the tools that we use to experience it use primarily spatial notions. They didn't call them 'Navigator' and 'Explorer' by accident, they were expensive branding exercises (both carried out by the same company, whose name still escapes me). Mosaic, the original Browser's name, is much closer to the 'small pieces loosely joined' idea.
Google and Blogdex and Daypop are beginning to find other ways to think about them.
The most literal spatial view of the web was Apple's long forgotten Project X which displayed sites and the links between them in a 3D space you flew through. It didn't really work, because the dimensions didn't mean anything.
I remember back when I was building CD-ROM UI with Maf, Nikki and Chris, the number of times we fought aginst the plodding page at a time model that was put together largely because it could be laid out as a storyboard or slide presentation, but broke down as soon as you tried to build it. We always took the view that you should be able to get to anywhere from anywhere, and built products on that basis.
The most successful of these was 3D Atlas, which despite selling over 2 million copies has almost vanished from the web. The best I can find is this review and this old Windows demo, plus the fact it was banned in Morocco.
This really was a spatial interface, using the earth as its space. As you zoomed in, you could find countries and be presented with spatially relevant suggestions. I always wanted to make this a UI for the web, but the various companies involved fell apart in the CD-ROM market collapse of 1996-7, and I did other things instead.
Still, it did nudge Graham into creating the great website that is flags.net which, being a labour of love, has outlasted all the companies involved in publishing 3D Atlas. And to think it all started with the innocent question 'Graham, could you make us some flag icons for the lists...'