Dead Game worlds

[tesral]

I got hooked on the Seven Voyages of Sindbad myself.

[Thorn]

I've always like the Realms though all of them could be interesting.

[nijineko]

well, and technically, Oerth is part of a constellation of 5 parallel primes (from left to right = non-magical -> ultrahigh-magical; with oerth being the right-most). the least magical is our earth, or a subtle variant thereof. a number of famous individuals in the greyhawk setting have artifacts from our world, including a coke machine, a vcr, and a membership in the lake geneva tactical studies rules association.

the best write up has been done on the venerable greyhawk community boards of canonfire, here. this should give in one place all the varied bits that have been published or quoted in any part of d&d regarding the parallel worlds of oerth.