What events grant a stack of Nephalem Valor?

Solution 1:

A major event is anything that causes a yellow dot to appear on your minimap.

Most (maybe all?) of these events also has a corresponding achievement tied to them.

I believe this list is a comprehensive list of events.

c/p from the link:

Act I Events

• Jar of Souls (Confirmed)
• The Matriarch’s Bones (Confirmed)
• Carrion Farm (Confirmed)
• Last Stand of the Ancients (Confirmed)
• Eternal War (Confirmed)
• Revenge of Gharbad

Act II Events

• A Miner’s Gold
• Lair of the Lacuni
• The Rygnar Idol
• The Restless Sands
• Guardian Spirits
• The Crumbling Vault
• Prisoners of Kamyr
• Lost Treasure of Khan Dakab (Confirmed)

Act III Events

• Waiting for Reinforcements
• Forged in Battle (Confirmed)
• Blood Ties
• Tide of Battle
• Crazy Climber
• Blaze of Glory

The link also goes into more detail about each event.