This is a great resource for collectors. Below is a bunch of stuff that's on my radar as being Greyhawk:
D&D Miniatures:
Warpriest of Hextor
Aspect of Vecna
Aspect of Demogorgon
Aspect of Lolth
Cleric of Kord
Bugbear Champion of Erythnul
Cleric of St. Cuthbert
Aspect of Hextor
Blood Golem of...