zip ties, 12 inch long/wide, and the tiny 2 inch short and thin.
theoretically multi purpose repairs for broken shoe lace, improvised D-ring, remedy a semi-broken backpack waist buckle. although in extreme cases of a broken bone, theoretically can rig a splint, but may be a bandana is better than a one-way zip-tie.
5 ft duct tape wrapped around a marker pen. patching a rip in the pack, or that one time the sole separated from a boot.
the exped air pad comes with a repair kit, I bring that along when using exped.
also bring along a tiny multi tool needlenose, pulling thorns out, or other fine detail that fingernails can't support such as loosening/tightening the iced over crampon straps.
you know that red string that comes with glowsticks? weighs nothing, very durable, I keep one around. use for emergency sewing, or hanging stuff inside tent.
drinking straws. I slammed the car door on my fingers at the start of a trip, later on they swelled up to the size of kielbasa. I used the drinking straws to form finger baskets, and scotch taped. A few days later went to the doctor, he was impressed that I made this from fast food drinking straws.