Dental floss might well be the most versatile tool to carry around with you. Just look at some (and I mean SOME, not all) of the ways it can work for you. Hanging pictures, dog chew toy, art work, scrunchy...shoestring, clothesline, fishing line, and more right here.
Also, slicing and cutting things like cheescake
and making jewelry...
and even removing those gross skin tags around the neck area. Eeeewwww!