The thing I see about those are locked into a given premise, a mechanic. And once you have a specific method, it becomes incumbent upon creative people to muck up that method as best they can, to push the limits, twist it, bend it, see if they can break it. Because that's what people do with a dramatic hook.
Again, though, my favorite method is Pandora Star method, also similar to the Amber method, where you're wandering your own city/village/hive/whatever, and you lose your way for a moment, and then you turn a corner and woah, you're in a completely different place. And if you lose your way again there, you're either in a new place or you find your way back home. You don't feel the transition, it's like when you go in your building and you get off on the wrong floor and everything is different. And theoretically anyone can do it from anywhere. But most people don't. Those that do, that discover the knack of willing it to happen, that learn how to control it, control where they go and when, they can be guides.
The Pandora Star books have people crossing from world to world, transitioning seamlessly. This idea would have a waystation, a mysterious ancient city that acts as a central crossing, a traveler's rest stop, where you can re-equip or get maps for your destination, or what have you. When you head for the borders of the city, you never reach them, because before you get there, you always find yourself somewhere else, somewhere in the real world. That just seems more mysterious and adaptable, more story oriented and flexible to more different kinds of stories than a subtle knife or a stargate. You have a specific method, you're going to have people controlling it, and then we get into what structures there are, what permissions, what authorities, and that seems far too complicated. It just strikes me better that it should be something anyone can do, by accident or intention, and that frees us up a great deal.
I may be finding some free time here and there coming up; I can write up a preliminary sketch of my ideas if folks think it'll be intriguing to see. I have some thoughts on the general structure, but once we agree on that, some folks can try their hands at populating it with unique locations and businesses.
I would ask that we have someone who acts as an editor, to make sure all the pieces fit. The checks-and-balances part of me thinks this editor should not be a writing contributor themselves, but should have the authority to reject formal submissions or ask for rewrites of particular areas or elements so that they fit the general theme... once we agree on what that theme is. I know I am as susceptible as anyone to thinking my stuff is all hot shit, and I also know I can go overboard frequently enough. So that's why I suggest an editor.