I've been busy reading threads and below is what I've compiled. Thanks to anyone who has ever posted their findings in a thread related to Yor'sahj and the purple ooze. I'd love to fill in the blanks and add more spells where it might be debatable how many stacks they add so please feel free to contribute!
My research so far:
Effloresence - NO STACKS (I'd love to get this checked as my guess is it's supposed to act like Healing Rain/Holy Word: Sanctuary and give a stack on entry).
Lifebloom - 1 stack per cast. (NO STACKS on bloom)
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
Chain Heal - 1 stack for each person it bounces to.
Earthliving - NO STACKS
Earth Shield - NO STACKS
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 (Although one report of it blowing up the raid. More info needed).
Unleash Elements (Earthliving) - 1 stack
Beacon of Light - NO STACKS
Guardian of Ancient Kings - NO STACKS
Lay on Hands - 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
Atonement - 1 stack
Binding Heal - 1 stack to the person you heal. More testing on whether stacks on the Priest.
Desperate Prayer - NO STACKS
Divine Hymn - 1 stack per tick (i.e. will wipe your raid)
Echo of Light (Holy Mastery) - NO STACKS
Guardian Spirit - ??
Holy Fire (with Atonement) - 1 stack per tick. Do not use if you have atonement.
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 (Renewing Renew in Serenity Chakra with a direct heal only adds 1 stack from the direct heal and none from the renewing the Renew. Yes, there are probably better ways to express this).
Generally, most other abilities that are not used by a healing class will not add a stack.
Deathknight Anti Magic Zone - Possibly adding 1 stack per person under it.
Deathknight Bloodwordms - 1 report of adding stacks. Need more info please!
Deathknight Deathstrike - no stacks
Deathknight Death Pact - no stacks
Deathknight Rune Tap - no stacks
Druid Leader of the Pack - no stacks
Hunter Chimera Shot - no stacks
Mage Glyphed Evocate - no stacks
Paladin Divine Storm - no stacks
Priest Vampiric Embrace - no stacks
Rogue Recuperate - no stacks
Warlock Drain Life - no stacks
Warlock Fel Armor - no stacks
Warlock Healthstones - no stacks
Dranei Gift of the Naaru - 1 stack
Healing Potions - no stacks
Mysterious Potion - possibly a stack
Set Bonuses, Trinkets and Weapon Procs
No stacks. Use your Maw of the Dragonlord with no fear!
Abilities that Affect Stacks
Mage Ice Block - Clears stacks
Paladin Divine Shield - Still gives stacks
Further information needed for Hand of Protection.
Below are the main threads that I've come across that discuss what triggers stacks of Deep Corruption:
Yor'sahj Purple Ooze Clarification - http://us.battle.net/wow/en/forum/topic/3657443252
Yor'sahj and Purple - http://www.mmo-champion.com/threads/1037455-Yor-sahj-and-purple