I was counting the virtual world that contained the Giant's Drink minigame. Which reminds me: Otherland by Tad Williams. Shadowrun (visually referenced by the iconic troll skull in Wanda's bedroom) is slightly different; it's more of a modernity-meets-magic reference.
I just realized that Star Trek is one of these. They went back in time to present-day Earth several times. They also had people from our time end up on the Enterprise thanks to near-future cryogenic suspension or whatever. It was visually referenced by the transporter pads when Wanda and Sizemore returned from the Magic Kingdom and by the uncroaked Redshirt Warlord in the lineup.
Oh! <headpalm> Sliders, Matrix, Army of Darkness, Jumanji and Zathura, of course. Even Mortal Kombat (the movie) fits.