I have played shaman shaman 2's, its pretty OP, especially if one rolls in Burst DPS spellpower set, and the other is in a stats healing set. the CC and burst potential is really good. so is the ability to both throw heals off, or the dreaded totem kite rotation, ending up with you being slowed the ENTIRE time, and both shamans just zipping around in ghostwolf, its fun haha.
Other classes I have enjoyed playing with, are Warlocks and Hunters.
Warlocks and shamans just go well together, with their CC ability combined.
As does a hunter with its over all OPness with DPS, in combination with a shamans cc, heals, and burst ability.
So yeah.