Useful Macros

Pet Commanding

Command your pet to attack target:
/petattack

Command your pet to stay:
/petstay

Command your pet to follow you:
/petfollow

Command your pet to charge target, use Demonic Empowerment and attack:
/cast Intercept(Rank 4)
/cast Demonic Empowerment
/petattack

Spells

CD (press more than once):
/cast Metamorphosis
/cast Immolation Aura(Demon)
/cast Blood Fury
/cast Demonic Empowerment

Shadow Bolt and Demonic Empowerment:
#showtooltip Shadow Bolt
/cast Demonic Empowerment
/cast Shadow Bolt(Rank 13)

Incinerate and Demonic Empowerment:
#showtooltip Incinerate
/cast Demonic Empowerment
/cast Incinerate(Rank 4)

Soul Fire and Demonic Empowerment:
#showtooltip Soul Fire
/cast Demonic Empowerment
/cast Soul Fire(Rank 6)

AoE

Even tho most of the times you use Seed of Corruption, this macro can come handy in some situations:

/cast !rain of Fire

Other Useful Macros

Apply Grand Spell Stone with 1 button:
#showtooltip
/console Sound_EnableSFX 0
/use Grand Spellstone
/use 16
/click StaticPopup1Button1
/console Sound_EnableSFX 1

Focus if you have target, Clearfocus if you don't:
/clearfocus
/focus

Fear target on use, on use with Ctrl Fear focus:
/cast [nomodifier, target=target] Fear
/cast [modifier:ctrl, target=focus] Fear