I used those pool noodles as padding/protection from the rack, under my canoe gunwhales, they fit over the round bars on my rack. Just had to slice them.  I only have one set of rubberized brackets for the rack, so on the rare occasion I carry two canoes they come in handy.

I have also used a small section of pool noodle to fit over the aluminum gunwhales on my old canoe when paddling. My legs would rub on the aluminum channel and be a bit sore after a long day. All my boats are wood now so I don't need them anymore  :). I bet they have lots of other uses too for the McGuiver types.