it's excellent for deglazing pans as a way to make a quick, even more flavorful reductions/sauces. in other words, when you are done searing meat in a pan, remove the meat and leave the pan on the heat. Toss in a cupful of bone broth and scrape the pan. (Don't do this if you have burnt the bits in the pan, then it will only taste like burnt liquid. you're looking for browned bits). Then if you like to get more complicated with that you can add other flavors and continue to reduce. For example you could add mushrooms, herbs, spices, a splash of wine, heavy cream, etc. reduce a bit and if you want, strain for a smooth sauce.
You can also reduce it (boil the water out to achieve a more concentrated flavor and somewhat thicker consistency) and flavor it to make a sauce, exactly like above but without deglazing a pan.
you can use it to replace water in cooking anything you might want to give an additional meatier flavor, like certain vegetables. I find this to be a bit of a waste of perfectly good broth though, but you could do it.
You can add a bit to ground beef or pork while cooking to make the flavors of those meats less one dimensional.
If you're making say a tomato sauce, you could add some stock into there to give it an added punch.
Lastly, if you get really good at making stock, you can make a consomme, which is basically a stock that has been strained, then cooked again with more meat and veg and clarified with egg white. Consomme is delicious with incredible flavor and in the summer you can even serve chilled consomme as chilled gelled cubes!