Where are all the ghosts for Haunted?

There is a pretty good guide over at d3db here. It includes a spawn point strategy for farming the Act I ghosts. The diablowiki also has a concise listing here.

Lucious the Depraved - a unique Grave Robber - found in Cemetery of the Forsaken - Act 1

Dataminer - a unique Ghastly Gravedigger - found in the Defiled Crypt - Act 1

Drury Brown - a unique Ghostly Murderer - found in the Defiled Crypt - Act 1

John Gorham Coffin - a unique Grave Robber - found in the Defiled Crypt - Act 1

Fecklar's Ghost or see also here - Unique Enraged Phantom- Festering woods - Act 1

The Archivist - Unique Grim Wraith - The Unknown Depths - Act II

The Tomekeeper - Unique Grim Wraith- Realm of Shadow - Act II

The Tomekeeper can be found at the Realm of Shadow in Zoltun Kulle's Archives. The Dataminer can be found only in the FAKE Defiled Crypt with the Jar of Souls. John Gorham Coffin can be found only in the REAL Defined Crypt lvl 1(just where the door to the Chancelor's Tomb leads).

Lucious the Depraved - Cemetery of the forsaken

Dataminer - Defiled Crypt

Drury Brown - Defiled Crypt

John Gorham Coffin - Defiled Crypt

Fecklar's Ghost - Festering woods

The Archist - The Unknown Depths

The Tomekeeper - Realm of shadow

Note: These are random and rare spawns so it wont be easy to find them,also keep in mind to check dead ends.