More details so... for example
http://www.wowhead.com/?search=nature+resist+totem
Now if you have 2 shamans on raid, and 1st one will summons Rank 6 and the 2nd one summons Rank 5 of this totem, they will give you 130+85 nature resist, but i think they shouldnt stack. More shamans, more totems.
And I'm not sure about hunters aspects and paladins auras. I havent tested it yet, but i think when 2 hunters with http://www.wowhead.com/?search=aspect+of+the+wild ( low level hunter and high level hunter, for example hunter level 56 with rank 2 and hunter level 68 with rank 3 ) they will stack but again i think they shouldnt.
I hope I explained it better now.