i learned this two years ago and i use it all the time. well, every time i make gravy from pan drippings at least....
when making gravy from the drippings/juices from the pan...place a large ziploc baggy inside a large pyrex measuring cup (use it like a trash liner ya know?)--pour the juices into the bag through a sieve and let it sit so the fat can rise. once it has (about 10 minutes), carefully pick up the plastic bag and hold it over the pyrex. take a pair of scissors and snip one corner of the bag (taking care not to cut it all the way off and have it land in the cup.) let the juices drain into the pyrex....stopping as you get to the fat. (i usually do this near the sink and swoop the bag over to that when the fat approaches.) now you've got your fatless drippings!
What you want to know more?
Okay, add enough chicken stock to your dripping to make 3 cups. In a pan, heat some olive oil over medium-high, and saute 1/3 cup chopped shallots for about a minute. Then add 1 cup of sherry and bring to a boil for about 5 minutes while it reduces by half. Stir in 1 tablespoon of chopped fresh sage, and cook for another minute. Add those reserved dripping now and bring to a boil again. in a small bowl, whisk together 1/4 cup of flour (i use tapioca flour so it's gluten-free but all-purpose would do) and 1/4 cup of water--whisk it reeeeal nice. Add this to your boiling mixture. Cook for a few minutes while it thickens, stirring constantly, then salt and pepper to taste (maybe 1/4 tsp of each?) Very basic, but tasty. I effing love thanksgiving dinner.