This is a pretty simple exploit i found while on my dps shaman.
I summoned my fire elemental by mistake then used Totemic recall to gain the mana back. Then i saw that the fire elemental did not despawn!
To some this may be somewhat old, but im sure many do not know this yet.
To keep your elemental without wasting 699 mana, just summon the totem, then quickly use Totemic Recall, and shazam, free fire elemental.