Nature resistance is the most useful resistance in Ahn'Qiraj, and also for anyone tanking Venoxis in Zul'Gurub. Its also useful when fighting Hunters, Rogues, Druids or Shamans. In TBC, the first boss in Serpentshrine Cavern requires a tank with heavy nature resistance and two with at least some. In Wrath, killing Loken without avoiding the aoe blast Nature Resistance is useful. Hunters have Aspect of the Wild and Shamans have Nature Resistance Totem, which both give 130 Nature Resistance. Remember to use them once in a while.