Now that I'm through 7 out of 9 chapters for the Dragonlance book, I have plans on moving to another book to review. I'm still going to continue my Key of Destiny review once I get a non-ancient computer and transfer the files successfully (I don't know how long that will take), but in the meantime I can review other stuff.
I decided to highlight some settings which are relatively unknown among the greater playerbase, or whose influences are relatively muted in the Pathfinder era. We know plenty about Eberron, the Forgotten Realms, and other flagship products, both due to setting history and popularity. But even games like Ravenloft have been passed over in favor of more classic fantasy.
Edit: I also submitted the same poll to rpg.net, so I'm taking their choices into account as well.
So here are my choices:
Cerulean Seas: An underwater campaign sourcebook and undersea environment for Dungeons & Dragons. After a great flooding plunged 99% of the world underwater, the civilizations of the sea grew dominant. Selkie fey live in traveling iceberg cities, marid nobles live in the underwater ruins of a pseudo-Arabian empire, priests of nature deities create guardians of living coral to oversee the reefs, a race of crab-people forge superior weapons near thermal vents, and aquatic drow and aberrant horrors lair in deep sea trenches, and more! Dungeons & Dragons in the sea!
Dragonmech: Shards of the moon fell to the earth along with titanic alien dragons, shattering much of civilization in the process. One of the only ways to fight them and other horrors requires the use of giant mechs, along with game stats. Shambling undead horrors, colossal golems, living trees, and other "fantasy mechas" predominate. Dwarves are the dominant civilization in the game, not humans.
Midgard Campaign Setting: A world inspired by Central and Eastern European folklore for the Pathfinder RPG. Notable for being set on a flat world surrounded by a world-serpent, capricious gods beyond morality who wear masks to disguise their divinity, a clockwork city full of kobolds, a mighty empire where arrogant dragons rule and seek to expand their boundaries for more wealth and power, and a network of ley lines and shadow roads used by the elves in ancient times to power their magic and travel across the world.
Midnight Campaign Setting: 2nd Edition version for the 3.5 rules. Basically like Lord of the Rings, but if Sauron won. The land of Aeryth is under the grasp of the dark god Izrador, whose legions of monstrous soldiers, clergy of evil priests, and wicked men and women enslave and oppress the populace. Magic, weapons, literacy, and most non-human races are outlawed. The PCs are resistance fighters against Izrador's reign, powered by ancient lineages.
Setting is notable for an alternate feat-based spellcasting system, where potentially anybody can be a spellcaster, as well as "destinies" which grant special abilities and spell-like effects to PCs based upon lineage (you are the last in a lineage of kings, you are blessed by one of the gods of light, etc).
Pirate's Guide to Freeport: A system-neutral book for Green Ronin's pirate city. A rough and tumble place on a chain of tropical islands, which were once the center of civilization for sorcerous serpent folk. There are also rules supplements for the book for various game systems (Pathfinder, Savage Worlds, FATE, etc): I might review them as sort of a single "pseudo" overview.
Ptolus: Monte Cook's City by the Spire: An urban-based setting used as the backdrop for playtesting 3rd Edition. Set in the world of Praemal, a spire was erected in ancient times by a being of great evil, and over the years many folk flocked to the area, forming cities and underground complexes around the region. Eventually the being fell (or disappeared), and now the region is home to the city of Ptolus. It is a haven for delvers seeking to explore the dungeons below, spellcasters and exotic races fleeing persecution in less tolerant lands, and all manner of travelers and traders drawn by the city's history and riches. Contains a well-detailed city, enough adventures to take PCs from 1st to 20th level, tips and advice for urban campaigns, designer notes by Monte Cook, and several of the more notable dungeons.
Ravenloft Campaign Setting: The 3rd Edition version developed by White Wolf as a 3rd Party Publisher. A D&D setting with elements of Gothic Horror, this iteration takes a departure from the others and makes adventurers native to the setting as the default. The world is set in the Demiplane of Dread, a sapient and malevolent entity which manifests in other worlds as mists, taking in individuals and entire pieces of land into itself. The Demiplane enjoys tormenting good and evil folk alike, throwing curses of poetic justice to wicked people, while making it hard to be virtuous in a land suffused with evil. Also has a "Gazetteer" series, where a woman scholar at the behest of a lich king visits the domains of Ravenloft, cataloging its people, cities, and interesting places by country. I'll review those as well if this is picked.
Red Tide Campaign Setting and Sandbox Toolkit: An Old School campaign setting which uses the Labyrinth Lord ruleset (retroclone of early 80s Basic D&D). For 3 centuries the last remnants of civilization clung to the Sunset Isles, their homelands fallen to red mist which spawn monstrous horrors and drive people insane. The mists are a hundred miles off the coast, but slowly making their way across. In addition to these dangers are the Shou tribes of the west, who resent these new intruders in their homeland. The setting has some Asian inspirations, with the greatest nation on the Island being based off of Imperial China and a Japan-esque Shogunate which has being taken over by devils.
Spears of the Dawn: An Old School setting using its own self-contained ruleset, based off of African myth and legend. In it, five mighty kingdoms entered into an alliance against the Eternal, an evil empire of undead sorcerers who sought to take over the world. After many wars they were pushed into the inhospitable deserts of the east, yet still their unliving legions and agents pose a threat. The kingdoms created an organization known as the Spears of the Dawn, traveling adventurers who defend communities and delve into Eternal tombs, risking life and limb. It has been a long time since the Eternals posed a threat, and now the kingdoms have turned to their own affairs and renewed ancient rivalries. The PCs are Spears who travel the land in an open-world style of gaming.