• Earth & fire elemental, fire nova, searing & magma totems stack. Obviously since they do damage.
  • Healing totem stacks, mana totem does not stack.
  • Frost, nature, fire resistance totems do not stack
  • Strength of earth, stone skin, windfury, flametongue, wrath of air do not stack (they provide a buff).
  • Totem of wrath buff does not stack, however ... if you are glyphed for it, it's worth to drop multiple and replace them with a damaging totem, as you will retain the glyph buff for 5 minutes on each toon that did cast ToW
  • Tremor & cleansing totems are 'pulsing' totems, they have an effect every x amount of time. Thus stacking them (i.e. drop them at several times) will result in a faster response.
  • Mana tide totems should stack as far as i know.
  • I stack my grounding totems as well (i.e. they are on round robin).
  • Same for my earthbind totems.