Save in Multiple Formats at once.
It would be a HUGE time saving feature.
It is such a waste of time to have to save each individual file I am working on separately. It would be great for instance to be able to save in both ai and pdf formats at the same time. As well as being able to save every file simultaneously in the chosen format / version.
Saving files in Illustrator is a truly Tedious, long drawn out affair.
And of course being able to save in the background so you do not get locked out of other files you are currently working on.