Good gravy should have only enough fat to allow the flour to thicken the liquid — much more and it becomes greasy. You can remove fat from stock by spooning it off, but a much easier way is to use a fat separator. It's like a measuring cup, but the spout comes from the bottom so the fat stays behind as you pour the liquid.
This new four-cup model from Oxo improves on the basic design with a non-slip rubber handle and a strainer. But the best thing is its rubber stopper that prevents fat from rising in the spout. And if a bit of fat sneaks in, plunge the stopper once or twice and it'll push the fat back into the cup. Remove it before pouring. This separator is available at Bed, Bath & Beyond and Sur La Table for about $15.