They aren't good for much, but you can recycle them. Make it easy to tell what devices cords belong to by writing on the tag then clipping it to the cord.
You can also use a tag to mark spare keys before putting them away in the junk drawer. one other idea is to use one on the end of tape before you throw the tape in the drawer. That way you won't have to pry the edge of the roll the next time you need it.