Being full of caffeinated vanity this morning, I'd have to say the collaborative homebrew brewed up by me and mine friend Steve has, hands down, the best "fluff" we've ever seen.
Give us an example, you say? Well... from the current adventure.
The Shrine of St. Tart's Bodice, located on St. Tart's Isle, due south of the islands of Marginal and Petit Soir in the Swollen Ocean (did I mention I stole most of this?): a temple that houses a great, not-to-mention low-cut relic of the church of Aja Opal Blossom, former courtesan, current Goddess of Love. The temple is run by the ravishing Mother Superior, and slightly-less-than-ravishing Sister Inferior, and staffed by priestesses who devote their lives to giving succor to wayward sailors.
Fun fact #1: the priestesses of this order can only recover their spells after reaching what D.H. Lawrence quaintly would have called "their crisis".
Fun fact #2: the shrine was formerly a military outpost last governed by the womanzing Captain Guillome-Goa Appolinaire, and was commonly known as Slick Guillie's Fortress, until the day it was overun by an all-female band of pirates in service to the Mother-of-Storms. This was accomplished with the aid of Guilllome's lieutenant, an engineer named Hobert-Apu, who was secretly in love with the pirate's leader. Hobert's betrayal was eventually discovered and he was tried and executed by being hurled bodily into St. Tart's Bay via the magical catapult he himself had designed, after the island was taken back from the pirate forces. The catapult emplacement is now known as "Hob's Lobbing".
Fun fact #3: the shrine is currenly under assault from a band of island-hopping, grass-skirt wearing, brown-supremicist tribal warriors know as the Polyneecheeans. The Polyneecheeans --whose name derives from their late, great philosopher-king Nee Chee-- originally hailed from Tiki-Ishii, an actively volcanic island which served as both their home and god. After the eruption which killed %75 of their population, the Polyneecheenas Diaspora began, scattering their tribes about the Swollen Ocean, with most eventually settling in the Ping Island Cluster, which consists of the islands Big Ping, Little Ping, Ping 3, Pang and Pong.
The Polyneecheeans' entire ethical system is based on skin tone, with their own nut-brown color setting the baseline of "good". As well as the belief that they are the Master Race. Since the explosion of Tiki-Ishii and their subsequent depopulation, they have built of reputation as fierce raiders, particularly of lighter-skinned women, even more particularly, blondes, who occupy a special place in their moral schema, being both "bad" and "highly desirable". Their warrior's cocoa-butter smeared faces, wild war cries --"Ocole!", "Mele Kamiki-Maha!"-- and unmistakable aroma of coconut oil have stricken terror into hearts of civilized people for hundreds of years...
Beat that!
(I should probably mention that I am, in fact, part Polynesian...)