Deer around here don’t have a lot of fat, but maybe those corn-fed east-river deer have more fat than ours. IME, anything but beeswax candles smell bad enough when you snuff them that it almost makes me wish I hadn’t lit them. I would hate to depend on animal fats for lamp-light. It’s gonna smell bad when you burn it no matter what kind of scent you use to try to mask it.
If you’re rendering the fat anyway, you could mix it with BOSS and other yummy seeds to feed your poultry during the short-day seasons. Melt it, pour in your seeds, mix & mold. Just be sure you don’t leave your mess for your lady! If you get too much for your own birds, you could approach a locally-owned ag supply (if you’re lucky enough to have one) and see if they’d be willing to sell them for you. There’re always fall farmers markets and folks who would buy them for wild-bird feeding if you incorporate a ribbon or wire for hanging.
Soap is a good use for excess fats you don’t want to consume or feed to your animals. There was a lady around here who used to make soap from bison tallow. Any fat will work, preferably well-rendered (a very stinky process, I hear). The harder the fat, the harder the soap.
Other personal care products could be made with animal fats—lotions and other moisturizing products—but we humans tend to prefer botanical fats for these types of products. For long-keeping, lotions and similar need a preservative or refrigeration.
If you have furry friends like dogs and cats or other predator pets, fats can be a valuable addition to their diets so long as you don’t overdo it, especially for skin and coat health.
You can use these fats for cooking and I see no reason not to. The main thing is to render them out well and not take them to their smoke points. Obviously you can’t store them on the shelf like you would with super-refined fats, but as long as you refrigerate and use them promptly or freeze them, if the animal is good for food, so are the fats. You just need to suit the fat—its flavor and smoke point—to your use.