I would love for there to be a way to travel between worlds.
I could see this happening in two steps.
The first step would be to allow the game to remember your inventory when you exit. So, I mine 64 diamonds in map A. When I load map B, I have 64 diamonds; if I put them in a chest before exiting map B, next time I load map A those diamonds are no longer in my inventory. This would allow you to move resources from one map to another--effectively using one or more maps as "mining colonies" to supply building projects on your "big city" map.
The next step would be to "link" maps together: When you reach the edge of the world, the game asks you: "Exit this map and load the adjacent one?" If you say yes, then you exit your map, and a new world is generated that is considered adjacent to the old one. You are even spawned at a point corresponding to your position on the former map. So if you were at x=75, z=431 on map A, you will spawn at x=75, z= -431 on map B.
Once map B has been generated, the -z side of map B will always be "adjacent" to the +z side of map A.
As a further perk, the game could remember which map you last played. So if you last played B, you will be informed of that upon starting Minecraft. Then you have the option of either loading B and walking back to A, or you can take a shortcut and just load A. Everything will be as you left it, except that you will have in your inventory whatever resources you acquired while you were playing map B.
This would be a way to compensate for the inherent limitations in world size in the 360 edition. Since you will never have more than one map running at a time, you are not using any more system resources than before. But you get many of the benefits of a really large world.
Not being a PC gamer, I had to look both of those up!
It would be like multiverse, I guess. Too bad Multiverse is a mod--the only way to get it on xbox is if 4J incorporates it into the main game; but as I understand it, they are only porting Minecraft itself to xbox, not mods. Oh well, one can always hope.
I like this idea. I don't think they need to be adjacent, per se, but linking them to allow trade would be awesome. This would allow other things, too. If a player is really into farming and crafting they could make potions, weapons, armor, food, etc and trade with other players. Also, if a seed is poor in resources, or has exhausted its resources, they could trade for things needed/wanted. The downside I can see with this your buddies cold just start new seeds, stripmine it, then start a new seed and/or just have your friend go into creative mode and produce a ton of the things you want and bring it over to your survival map. Not a huge deal and the fix would be easy (I would think) - tag creative mode items so they cant be taken to other seeds.
The way I see it working would be a new kind of portal. Although I like your idea of linking your own maps together your way, I don't think it will ever happen. My idea would be to introduce a new kind of portal that can link to your friend's world. These portals would have to be built (most likely with rare materials). Once you build the portal, you are prompted to invite your friends. If they accept the invite, a portal appears I'm their world which teleports them to your world.
Not trying to highjack your thread, didn't want to start a new one since yours us similar...