The usefulness of this totem is specific in PvE but invaluable for those situations. It is excellent versus the corrupted druids in Wailing Caverns, since they can sleep party members.
Against mobs that have an AoE Fear, this totem should be placed immediately, and in a central location to the fight.
This totem will immediately remove any applicable ailments when it is first down, then subsequently attempt to remove fear/sleep/charm effects every 3 seconds.
Don't care about your choice of spells if you are fighting between obstacles. Tremor will clean the effects of fear/sleep/charm and the player won't spam the totem each time he has an obstacle.
Although it is excellent totem in raiding, don't forget it has its PvP uses.
Patch 6.0.2 (14-October-2014): Totems will no longer cause hostile creatures to enter combat with the Shaman based on proximity.
Patch 5.1.0 (27-Nov-2012): All totems are now considered spells, and summoning totems can be prevented by silencing effects. Searing Totem, Magma Totem, and Fire Elemental totems fall into the Fire school, while all other totems fall under the Nature school.
Patch 4.0.6 (8-Feb-2011): Tremor Totem has been redesigned. The totem is now usable under Fear, Charm, or Sleep effects, and pulses much more rapidly, but lasts 6 seconds and has a 1-minute cooldown.
Patch 3.1.0 (14-Apr-2009): Now correctly pulses every 3 seconds, up from 1 second.
Patch 3.0.8 (2009-01-20): Tremor Totem's duration has been increased from 2 minutes to 5 minutes.
/Patch 3.0.2 (14-Oct-2008): All totems are now considered on the "Physical" school, and no longer magical spells.
Patch 2.4.0 (25-Mar-2008): Tremor Totem now pulses every 3 seconds, down from 4 seconds.