I try to do this with lots of creatures in my games and the HOW rules book hints at that as well with some creatures found within. I take this from both a study of cultures historically and from my own experience hunting. Every part of a creature is used if at all possible, and it struck me as odd from an early age that creatures killed in adventure game combat were just left strewn about the dungeon or battlefield.
Sure there could be "dragon armor" in some games but that was usually it. What about a manticore's tail turned into a mace with shooting spikes? Green slime grenades (green slime in glass vials)? Giant snake fangs turned into daggers with a poison delivering center! It's amazing, once you begin planting the seeds of the vanquished being more refuse, how creative your players will become in thinking of ways to use or try to use the remnants of the defeated foes.
In general I use a (mental) calculator kind of like the old ECON 101 supply v demand graph. In my case its Rarity (supply) v Danger (demand).