I was going to say first aid kit, but actually, over the years I've used most items from it, including plasters, painkillers, scissors, needle and thread, superglue and strip of fabric repair tape. The only never used item in there (so far!) is a length of tubigrip bandage. I have to admit I can't remember the last time I used my compass in anger, though I do get it out occasionally for practice or to show the kids how to use it. I do carry a survival blanket on day walks which I've never used, but not in multi day walks when I reckon my sleeping bag / tent would do the same job. Interesting question, though!