Killer of socks, mangler of flesh. A protruding nail in a hardwood floor is a hazard. Chances are it will rear its ugly head again and again. Fix the problem permanently by prying out the offending nail with vise-grip locking pliers; rock the pliers against a block of wood to keep from denting the floor. In the nail's place, sink a trim screw of similar length, and cover with a dab of wood filler.