Druid
 Effloresence - NO STACKS
 Lifebloom - 1 stack per cast.
 Rejuvenation - 1 stack on initial application
 Swiftment - 1 stack on the person swiftmended.
 Tranquility - 1 stack per tick (i.e. a raid killer)
 Wild Growth - 1 stack for each person hit by Wild Growth

 Shaman
 Chain Heal - 1 stack on initial hit only (although I'd like a bit more testing!)
 Healing Rain - 1 stack upon entering. If you leave and re-enter, you gain another stack.
 Healing Stream Totem - NO STACKS
 Riptide - 1 stack on initial application
 Spirit Link - NO STACKS

 Paladin
 Beacon of Light - NO STACKS
 Holy Radiance - 1 stack for initial application (i.e. if it hits 4 people, 4 people get 1 stack).
 Word of Glory - NO STACKS

 Priest
 Atonement - 1 stack
 Divine Hymn - 1 stack per tick (i.e. will wipe your raid)
 Echo of Light (Holy Mastery) - NO STACKS
 Holy Word: Sanctuary - 1 stack upon entering. If you leave and re-enter, you gain another stack.
 Holy Word: Serenity - 1 stack
 Lightwell - 1 stack per buff gain (i.e. when the person clicks)
 Penance - 1 stack for the whole channeled cast (i.e. not 1 per tick)
 Power Word: Shield - 1 stack (even when glyphed)
 Prayer of Healing - 1 stack
 Prayer of Mending - NO STACKS
 Renew - 1 stack on initial application


 Other Abilities
 Deathknight Deathstrike - ??
 Druid Leader of the Pack - no stacks
 Hunter Chimera Shot - no stacks
 Priest Vampiric Embrace - no stacks
 Rogue Recuperate - no stacks
 Warlock Healthstones - no stacks