This is a feature that's been missing since ever: the ability to backup the content of a whole sim externally.
For example, if you are a builder and building a whole sim from scratch (or with other stuff) and a forced to put the sim down, since you don't have the money anymore to sustain it - or your customer, whatever - taking down the sim means taking down all the labour cost, all the work. If you want to put the work up later, again, you've got to start more or less from scratch.
In this case it would be very nice to have the ability to backup a whole sim and store it somewhere for possible future use. At the moment this isn't possible, to this is a big, missing feature in the portfolio of Second Life.