The freezer portion of the large fridge tends to go unused and it would be really amazing if fridges could be stacked for extra space, mini fridges would be perfect for this!
Essentially it would be a single block version of the fridge containing only the inventory portion.

Now that I think about it, separating the freezer into its own block might be a good idea too, as freezers often come as a separate unit. They may even be stackable to form the existing fridge.