The Meaning of Life, the Universe, and Everything.
Perth, Western Australia
Being able to choose say, 8 chunks anywhere on the map to keep loaded all the time would be great, or more chunks depending on how much memory is allocated to the server/client.
Or just having the option for the /fill and /setblock commands to temporarily load in the chunks, make the block changes, and then unload the chunks again, which would have less impact on servers and presumably the clients too.
It's very frustrating making a map only to find out you can't do randomised loot chests because you don't want the map in the spawn chunks with the redstone.
I'm not sure about a chunk loader, but being able to temporarily load in chunks with /fill and /setblock seems useful.
Either that, or Minecraft has a queue of actions to be applied to unloaded chunks as soon as they are loaded. When using fill or setblock in a chunk that isn't loaded, Minecraft will put that action in it's queue, and will tell the player that an action has been added to the queue rather than done immediately. If the player leaves while the queue still has actions in it, the queue will be saved to the world file.
In order to prevent possible chaos, the queue will have a maximum number of future actions that can be assigned to it. That way, in the event that you have a command-block going crazy, you don't have to save a world with a queue that says to preform millions of actions on a chunk that isn't loaded.
I get offtopic a lot, be warned. I also often mention a Minecraft clone called Minetest. The clone is nowhere near playable with it's default game in my opinion, but it's at least the start of a good open-source voxel rendering engine, and maybe one day it might be decently playable.