It also just occurred to me that at some point I said I would post a list of Greyhawk languages for sombody's PC, and that I never did it. So I seek to rectify that problem:
Common (a combination of Ancient Backlunish and Old Oeridian. Widely used across the Flanaess)
Baklunish (mainly spoken by the tribes of the Plains of Paynim)
Oeridian (widely spoken across the Flanaess)
Suloise (this language became all but extinct when the Rain of Colorless Fire devastated the Suel Empire. Useful for delving into the arcane tomes of the forgotten Suloise)
Flan (mainly spoken by the Tenha)
Ferrel (a Oerdian dialect spoken by officials of the Iron League)
Nyrondese (a High Oeridian dialect spoken by peasants, shopkeepers, etc in Nyrond)
The Cold Tongue (a Suloise/Flan admixture spoken by the barbarians of the Thillonrian Peninsula)
Velondi (Old Oerdian dialect spoken by rural folk near the Veluna/Nyrond border)
Keolandish (Old/High Oeridian dialect spoken in and around Keoland)
Lendorian (obscure Suloise dialect spoken in the Sprindrift Isles)