I got this idea the other day, and I know of a couple of other games that pull this off really well.
Essentially, a lockbox is an item in which a player can store one item, or a set amount of gold. With this, they can bury it anywhere they would like to in the realm of Tamriel to "hide" it or store it away, with risk of other players randomly digging it up. It is signified by the dirt being raised over the area it is buried, and will disappear in after a set amount of time.
I don't suggest this for the storage capabilities, but more for Role Players. Just the other day I saw a bunch of RPers together and one of them sent a lower level off on a "Quest" to go find an item and bring it back to him. I think it would be cool for RPers to take the box, bury it some tomb, and send others off to find it. Or for something like a giveaway, where someone puts a random item (Deadric Motif or something) and hides it in a zone for a group of players to try and find.
Let me know what you think, I think this would be a nice little thing to add a bit of immersion for RPers and other small things.