I find the categories in the Activities Overview's applications list rather useful when it comes to certain groups of applications which I use, however I have to go all the way into the list to get the grouping which should make it much easier to access certain applications which are perhaps used together (I mean categories such as Sundry or Utilities).

So I think it would be rather useful if one could 'Favourite' these and make it so that they stay in the dock. Then perhaps when clicking on them a long thing could come out of the dock with the icon lists of the various applications in the list, or some other way of allowing the user to select the application they wish from the category.