Marash red pepper flakes might just be the most famous spice you've never heard of. It's been used for years in restaurant kitchens, like that of the famous Chez Panisse, though you don't often see it on the menu.
I only discovered the pepper recently after inhaling an appetizer of tuna carpaccio at a local restaurant. It was so subtly and beautifully seasoned that I had to know how it was made. The waiter listed off several fairly normal and expected ingredients, paused to think, and then said, "Oh, right. And marash pepper flakes." I had to know more.