Lands of the Flanaess (an overview of the nations for new players. Indispensable reference for character creation).
Races of the Flanaess (includes info on placing Dragonborn, Tieflings and adds Snow Elves!)
Languages of the Flanaess (very thorough listings and useful in giving that Greyhawk feel to a character)
Classes (there is a lot of new paths, archetypes, etc)
- Barbarian: Path of Vatun, Path of Totem Warrior
- Cleric: Animal domain
- Druid: Circle of Celene, Circle of the Sun
- Fighter: Brigand, Cavalier
- Monk: Way of Glory Everlasting (Hieroneous), Way of the Gray Hand (Hextor), Way of Rao, Way of the Fist (Zuoken), Way of the Scarlet Sign (Scarlet Brotherhood)
- Paladin: Oath of Obedience
- Ranger: Guardian
- Rogue: Beggar
- Sorcerer: Bitten by the Serpent, Touched by the Wind Dukes
- Warlock: Elder Elemental God (patron), Rexfelis (Cat Lord patron)
- Wizards: They have no entry but are covered in their own book, Wizards of the Flanaess 5E.
Kudos to Joe on another high quality work. I know I'll be implementing this book for all my future 5E campaigns. Wizards of the Coast take notice!