Here’s a hot farming spot if you’re playing the WotLK version of WoW, i.e. Wrath of the Lich King. It’s one of the best spots I know of that requires no professions. There is a place in The Storm Peaks that is packed with elementals that drop crystallized fire, relics of ulduar, grey items and a chance for some green/uncommon and blue/rare armor and weapons. It’s the Crystallized Fire and Relic of Ulduar you want, to sell expensively on the auction house.
The place is quite small and often farmed by both factions. However, the respawn rate of these mobs is tremendous and you’ll rarely run out of mobs.
The mobs you want to target are called Seething Revenant. Here is a map that shows their location:
Seething Revenant mobs in The Storm Peaks