There has been some discussion before about rendering lard and using it for cooking, as well as a suggestion of using bacon grease when making mayo, but I don't know that there has been any mention of using "other" fats.
MacDonald's, of course, had better french fries in the days when beef tallow was included in the frying oil.
But my real inspiration is an article I was researching about Mongolia's foodways, where just about everything is cooked in mutton fat. So when I cooked a leg of lamb last week, I saved the generous amounts of lovely, clear fat permeated with flecks of fond, chopped garlic, and cumin, to see if it was a good for cooking. It is. I first tried a small amount spread on a cracker, just to see what the flavor profile was like, and it was soft, not really oily feeling, and very flavorful. I just pan-fried some potatoes in it, and they were ultra-crisp and tasted wonderfully like they'd been cooked with the roast. Mongolians like mutton fat on rice, so maybe I'll try that next.
I wondered if anyone else had experimented with using animal fats other than lard.