I have Earth Shield to my target's target, or the target if the target's target is hostile.

Also have Riptide and Healing Wave assisting my tank.
/cast [target=targettarget, help] Riptide; [target=targettargettarget, help] Riptide; Riptide.
(Note I use a target based system, so all shammies target my pally by default).

In Jamba, I have it set for when a given toon gets below 66% health - the raid warning is Press G4, or whatever.
Something like /cast [target=ToonD] Healing Wave.

I have one key for all the shammies to Lesser Healing Wave, basically the same logic as Riptide.
This is for support/burst healing, if the Resto needs a bit of help.