Roasted a duck tonight, so I have two jars of duck fat in the fridge.
They join a container of chicken fat, and one with the rendered fat from a prime rib.
Tried to make beef gravy with butter one time, not so good , definitely need beef fat.
I’ve been told by a Brit that if you’re making a Full Breakfast with mushrooms, they MUST be fried in beef fat!
I save all the beef fat rendered in my cooking, but I don’t always manage to use it before it gets moldy. 
I have two jars of bacon drippings and a pint++ of duck fat. Normally I have about 2 quarts of turkey fat + broth and several bags of pork fat trimmed from butt roasts and shoulders and chops, but a hurricane-driven power outage ate lots of what was in our freezer, this included. I have never bothered saving beef tallow. Can usually substitute pork and if not can buy lard from the grocery store.
Butter, some schmaltz capping some gelatinized chikin broth and a nice tub of rendered manteca from the local tienda. Basically bacon fat without the nitrates and salt, leftover from them making chicharrones. They’ll sell you like a quart of the stuff for four bucks, it’s pretty sweet.
Only when the wife goes for her fucking Coffee Creamer.
I have goose fat, duck fat, and a can in which I collect the fat I plan to throw out. (skimming chicken broth and beef dishes. We don’t cook a lot of pork.) Oh, and butter, of course.
Oh, they add sugar? 
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I have butter, ghee, and bacon fat. I used to keep the olive oil in the fridge, but I buy a smaller size now.
What do people use their chicken or duck fat for? If you were to saute vegetables in it, would they taste chicken-y?
I’ve recently fallen in love with smoked duck, so I’ve got a good amount of duck fat in the fridge. I use it for grilled cheeses and scrambled eggs. It imparts a much deeper flavor than butter does.
I’m trying to get my wife to use it more, but she’s stuck in her ways.
I use the goose fat the pop popcorn, and to saute vegetables. It imparts a lovely rich flavor. Like butter, it’s not overwhelming, it just tastes nice.
The duck fat has a stronger flavor, and isn’t as suitable for popcorn. It’s good for vegetables, although I prefer the goose fat. But where it really shines is in making bean soups. My husband and daughter don’t eat pork, so I don’t add a ham bone to the split pea soup. Instead, I saute the carrots in duck fat. It adds a similar unctuousness to the resulting soup as a ham bone would.
Really, anyplace you use bacon fat, you can use duck fat.
I don’t bother to collect chicken fat, but my dad always saved enough to fry the potato pancakes in it for Hannukah. (Usually mixed with some peanut oil.) It’s a nice, reasonably-high-smoke-point fat for that, and its traditional.
I have butter, browned butter, lard, and bacon fat.
The butter is obvious. The browned butter gets used in recipes. The lard was for a recipe that never ended up getting made. And the bacon fat always seems like a good idea when I’m collecting it, but never gets used.
Roast potatoes.
I get beef fat from our home-made burgers (using a George Foreman grill), but sometimes I have to top it up by buying dripping (beef fat).
To prevent it going mouldy, every month or so I melt it all down, let it set, pop it out of the container and scrape the bottom clean of any stock that remains, and wash out the container. I never have a problem with it going bad.
I use the beef fat for roast spuds. I also add soft lard when I make stock from the ham bones and skin after summer.
While I like duck or goose fat, I’d have to purchase that specifically, and I cannot really justify it.
Butter, ghee, and shortening. Butter because, duh. Ghee as a condiment and also for higher temp pan frying. Shortening for a wide variety of baking (Mrs. Lines, as while I can cook, I have the touch of death for baked goods unless it’s from a box). Whenever I cook a duck, I keep the fat, mostly for cooking cubed potatoes, but sadly don’t cook it all that often (Mrs. Lines has gone largely vegetarian, and cooking a whole duck for myself is too indulgent). Bacon fat of course whenever I cook bacon, but recently I’ve been using European style bacon which has so much less fat I barely have enough to cook the burgers for bacon cheeseburgers. 
Another one I love to use but have rarely is lard if I do a slow roasted pork belly. The combination of smooth creamy fat is perfect for adding that bit of mouthfeel in any number of slow cooked dishes, especially since I’m often using pork loin rather than fattier cuts. This way I can add a controlled amount back into the dish, which would otherwise be a smidge too lean.
duck fat is used in fancy restaurants for frying french fries
Finally got the last bit of my bacon fat used up. Beyond butter, I don’t really typically use a lot of animal fats in cooking so I don’t normally save it.
However, I keep seeing all these mentions of duck fat, I might have to try my hand at cooking one soon. I wanna know personally what all the hullabaloo around duck fat is about, plus it’s a good excuse to eat something I never have before.
How much fat can I expect from one duck?
Just a tub of bacon drippings in the freezer. When it gets full, I knock it loose and it goes into the compost and I start over. Other than that, just Irish butter and some unsalted butter.
Depends on the duck and your cooking method. If you lightly prick the skin (sharp paring knife tip is good) over the breast and thigh area and do a mostly dry method, I’d say a solid 1/2 cup or so for the normal sized frozen bird from the store. Make sure to use the leftover meat and carcass for a wonderful duck stock which is a great base for a number of soups as well.
I use my chicken fat - also called schmaltz - for kosher-style cooking.
(As I don’t actually keep a kosher kitchen nothing I make is kosher, but other than that, there are some recipes where I use the same ingredients).
If I recall, any rendered poultry fat - so not just chicken but also goose, duck, etc. - can be referred to as schmaltz although it’s usually of chicken origin.
I do render the fat myself and then I park it in the freezer until I need it for a recipe. I don’t use much, and yes, it definitely has a chickeny flavor. That’s no problem if, say, you’re making matzoh ball soup which typically has a chicken broth base.
I also use it as an ingredient in my mom’s chopped liver recipe which, alas, I have not made for years because it’s more chopped liver than I want to eat in a short period of time and with just me in the house, well, I can’t finish it all before it goes bad (my late spouse also liked mom’s chopped liver, so back when he was still around I did make it from time to time).
The Jewish side of my family used to spread schmaltz on toast the way gentiles use butter, but that’s not a habit I ever picked up.
You certainly could use schmaltz for sauteing vegetables. It’s just another oil/grease you can use for cooking. Whether or not you like the result is entirely up to you. Some people do, some people don’t.
Our family traditional English roast beef and Yorkshire pudding Christmas dinner is cooked in beef fat. The roast and potatoes are cooked in a roast pan in about 1/2" of beef fat The potatoes are rotated in the fat at regular intervals to ensure the potatoes are more fried than roasted. The Yorkshire puddings (which are sort of popovers cooked in muffin tins) are made by adding a teaspoon of beef fat to each cup in the muffin pan, heating it, and adding the batter. And of course the beef gravy is made with a fair amount of beef drippings from the pan, which is 99% fat. The meal is probably 5,000% of the RDA of saturated fat, and SO delicious. We wash it down with plenty of red wine to help clear the arteries.
The leftover beef fat freezes well and lasts in the freezer a long time.
I like duck fat, but i wouldn’t cook a duck just to get the fat. I have duck and goose fat lying around because i like to eat ducks and geese.
Sadly, I won’t be roasting a goose this year. 
I usually have a big new year’s Eve party, and serve roast goose, Indian barbecued lamb, and a few vegetarian entrees (plus desserts) to lots of friends. Which reminds me, I should send out a “don’t save the date” email to the people I usually invite.