Personally, I'd find this beneficial, but I'm not sure what the community at large would think of it.
I'd like to propose this as a vote if people are receptive to this.
What I recommend is that land can have "texture overrides" associated with it.
So, every parcel of land would have a list similar to this:
Texture key to replace ---> Texture key to replace with.
(Similar to how movies are done now)
This list would only take affect when you are actually on the land parcel with the list. The substitution would be done 100% client side (no server load for doing this other than the initial download of the key pairs).
This came up in my mind because one of my new neighbors decided to make a set of billboards that clash with my land design. While I have no problem with those things being there, when people are on "my land", I'd prefer that those items are masked.
Again, it should only take affect when you are in the land in question. At other times, the original textures would be shown.
Is this an interesting idea (to be discussed further) or do people feel that it is a bad idea?