Homebrew. Current 4e campaign is heavily influenced by Star Wars, SG1, and Harry Potter, with side treks borrowing from Star Trek, Death Gate Cycle, or whatever TV show of the week that I liked, from Chuck to CSI. While I have a lot of modern and sci-fi tones in my campaign, it is a fantasy setting, in an impossibly large world with tiny pockets of civilization. Travel between civilizations is pretty much only possible with air ships. At high paragon and epic some gate travel options open up, though it's not quite as straight forward as SG1's gate travel, since there is actually a small amount of travel time through a hazardous Astral Plane. I'll shamelessly steal a CSI episode for a murder investigation, or a Leverage episode for a sting.
I'm a smorgasbord DM.