Hello,
1)Territories
It seems like this game needs some kind of protection from vandalism. My suggestion is to give each player *one* territory flag. This flag would give the blocks around it within a certain distance the property that they cannot be destroyed by anyone except the person the flag is flagged for. Flag cannot be placed closer than 'x 'to each other to prevent overlap.
The area should not be huge, but big enough for a home. Sadly this would not be big enough for a mega-structure.
Optionally, the area could expand out or shrink with time and player activity (keeping a minimum size at all times to protect the home). For example, a player who is active for a long time (does not mean he has to log in every day, but occasional over a long time, months, years) would see his protected area grow (you can toggle your view to see the protected area's - view toggle is another feature that would work nice here). With diminishing returns, there would be a soft cap on how big this area would be. optionally the area would shrink when the player has not logged in for a long time, but restore when he logs back in (and even grow a bit since at this moment he has been active for a long timespan). All this would depends on the actual distance between flags and so on.
Ideally, the game should be able to track the activity of a player in an area with the relative distance to his flag. If the game knows that a players build something close to his flag, the game could protect that from destruction with the message 'you cannot dig or build here'. The protected area should probably always be spherical. For example, if within a certain sphere within 30 squares of his flag the player has edited more than 1/3 of the blocks, then the entire sphere with radius 30 would be protected.
Flags are crafted for additional awesomeness (only 1 each player).
2) Personalized storage
These storages should be made from rare materials and/or should be limited in number for each players (lets say 2-3 personalized chests).
Two types:
* Personalized chests
This chest can only be accessed by the person who made it. Can only be destroyed by the player who made this.
* With a lock
Locked storage could have a number combination and is accessible to anyone who knows the secret code. Cannot be destroyed without the code. Cannot be destroyed when not empty.