The ash tree is fast-growing and makes excellent
firewood - unlike most wood, it even burns well straight off the tree. These facts make it extremely valuable for those who have space to grow trees and regularly need wood to burn.
Ash was sacred to the druids as well as the Vikings and their ilk; in Norse mythology, Yggdrasil, the world tree, was said to be an ash, and from it Odin carved the first man, Ask. The spear Gungnir, which he used to start wars on Earth, was also carved from the ash-wood of Yggdrasil. In Celtic mythology Gwydion, Odin's very approximate counterpart, made magical wands from ash. In Greek mythology, ash was sacred to the sea-god Poseidon.
Ash out of Evil Dead was apparently the model for the main characters in both Doom and Duke Nukem.
'Ash' also appears along with protein, fat and so on in the nutritional information for various snacks for pets. I have never been able to figure out why.