Special interests groups of webpages on the web have been handled by Webrings. If you look around the web you will see these on arcane webpages. The way they work is that one website is the ringmaster, so to speak, which has a list of all the other websites in the ring. If you have a website that you wish to place on a webring you email the URL to the ringmaster and he inserts your URL in the ring. You are given a bit of html code which gives the viewer access to other websites on the ring. You put this in a prominent place on your frontpage.
Some webrings are small and may have only a handful of websites, others are large. They are well used by people interested in povray imaging, 3D modelling using various techniques, VRML worlds, Bryce 3D landscape modelling etc.