How about things that we have carried on every single trip, but never used?
That includes a few things in our first aid kit, but we're HAPPY we haven't used those.
On this last trip, we never used the extra paracord I take--but I'll still take it next year. We ofter take more bug juice than we use...but we also never want to run out. We take head nets for bugs...they weight nothing and save your life when you need them!
The only other thing I have carried over the years that we rarely use are a pair of lightweight binoculars. But that's just fun.
Jim--you've NEVER used a compass? Do you ever go off-trail? I use mine regularly to sight off nearby landmarks for navigation...