Cook with it, definitely...a little bit is great for "sweating" the vegetable ingredients destined for a soup (especially gumbos and the like). A much more flavorful alternative to vegetable oils (and no worse for you when used in reasonable amounts).
I always saved the fat skimmed from a pot of chicken soup, from roasted chicken pan juices, and fat rendered from trimmed off skin or fat. I'll use it as a starter as mentioned above, but the primary use for the stuff is when I make matzo balls for soup, or bread dumplings to include in a pot of stew.
I also use it added to duck fat if necessary when I'm putting up some confit duck legs and I don't have quite enough duck or goose fat on hand (what can I say...to us Hungarians those things are staple items!)