Companions will assist you to (m)ove two or more tree trunks at a time. They will also assist you in putting up a building. While their actions logging may deprive you of experience, their assistance only seems to cut down the time needed for things like building and treating hides/furs. That's very useful when putting up a cabin or performing the time-consuming task to finish off a fur.
They may well be more skilled than you at skinning a kill. If perchance you have more than one deer, etc, to do, you could put him to work on one while you do the other. If nothing else, you'll get a good idea of how much time YOU would take doing the task, as you wait for him to finish it!
When you have them build a fire, their fires last a good while and require no wood from your stocks. They find their own.
I've had them cook meat for me. Their skills were not exceptional. Still, it might provide you better food than you are capable of making.