Maybe more a "Home Cooking" question, but maybe not. I routinely save duck fat for rendering when I get the chance. I've heard some people do that with chicken fat, and, of course, bacon fat.
Now I'm looking at quite a bit of beef fat that congealed on top of a beef stock (from meaty bones and shanks) after cooling, and I wonder why I always throw that out, and also pork fat apart from bacon?
Uses for various fats, or cautions?