Things like:
Druid:
Glyph of the Lifeshaper: Your cyclone now turns the target into a tree.
Mage:
Glyph of Obscene Power: While Arcane Power is active, you now levitate.
Glyph of Smoldering: Corpses of enemies slain by your Fire critical strikes are now charred and smolder.
Paladin:
Glyph of Ashes: Demons and undead slain by your holy damage have a chance to be reduced to a pile of ash.
Warlock:
Glyph of Disintegration: Enemies slain by your chaos bolt or incinerate have a chance to be reduced to a pile of ash
Shaman:
(Firstly, bring back the ascendance glyph that lets them be a coloured version of themself)
A glyph that allows enhancement shamans to cosmetically wield the appearance of the first 2 handed weapon in their bag.
You know, stuff like this?