WMG / Grand Unifying Guesses Cyberspace
aka: Cyberspace

The creation of ENIAC caused the creation of many worlds including:
ENIAC's younger sibling, UNIVAC, is insanely jealous that it didn't get to create any worlds, and is currently plotting a terrible vengeance. PC and Mac spend nearly every offscreen moment trying to keep the crazy old man in check.

The following universes are related by having alternate versions of each other's Cyberspace.

All digital worlds coexist, but use incompatible operating systems.
They all exist simultaniously but never interact with one another because they are incombatible with each other. A character from Tron can't travel to a Digimon world because the Digimon operating system can't run the Tron character's program. Attempting to join the digital worlds via the Internet creates The Web, as seen in ReBoot, which breaks down the programs of every digital character not native to The Web, preventing the digital worlds from interacting online.

Most World of Weirdness and furry webcomics which do not have space travel in them are set in a far-future revision of Second Life.
Jossed in the case of DMFA, as that is set in Furcadia...