Since it's my thread I'll start off with a sample culture.
A Culture, The Tanolani
The central tenet of Tanolani life is the natural cycles of the world. They belive that all things follow natural cycles of birth, growth, decline, and death each thing in it's own time. They view time as an endless coil of cycles within cycles. To ask when the world began or will end is as senseless to them as asking when a ring begins or ends.
To the Tanolani seeking to preserve ones work beyond ones cycle is a sin. In keeping with their beliefs they work only in materials that are part of the natural cycle of death and decay. Leather, cloth, wood and bone are the only materials they will work with. Stone and metal work is considered to be an act of hubris, of a man seeking to have his work outlast his place in the cycle.
They are a nomadic people generally keeping to a series of seasonal camp grounds. They are generally hunter-gatherers but sometimes will keep herds of sheep or other hair-bearing animals for cloth. While they are aware of agriculture they reject it. They live in teepee or yurt styled tents made from cloth or hides depending on the resources available. They prefer temperate climates and hilly terrain.
They dress in loose cloths decorated in bright colors usually set in knotwork patterns that represent the interlocking cycles of the world. They use inward curved knives made from claws or other monster parts (the jagged pads from the end of Displacer beast tentacles are prized.) Their usual hunting weapons are bows and spears, often poisoned with Int damage paralytic poisons.
They usually follow Druidic traditions and will use reincarnation rather than ressurection in the event of what they feel is an untimely death. They do vernerate some gods, but generally view gods of stone and metal work as tempter figures.
While they are uninterested in the usual trappings of civilization they do not seek to destroy or even denigrate cultures that do pursue these things, they feel that they will fall as their cycle demands however they try to avoid their fate. They will however defend thier lands fiercely and more effectively than more advanced cultures are likely to believe.
Classes:
Most Tanolani hunters are Rangers or Scouts. Paladins are very rare and tend to evaluate things very differently from standard paladins. Totemists are the most common class of warriors and are highly respected. Monks are unknown. Fighters are usually multi-classed. Rogues are rare. Soulknives are respected amoung those tribes that have had contact with psionic cultures. Barbarians exist, but are less common than one might think. The Tanolani tend to prefer stealth and ambush to frontal assaults. Dragon Shamans are rare but highly valued. While they are aware of the existence of Binders they find the Vestiges existence outside the normal flow of time very disturbing and the do not practice Binding.
Magic:
The most common spellcasters are Druids and Bards. Sorcerers are not unknown but Wizards are very rare as the Tanolani do not usually preserve their knowledge in written form. Clerics are rare but respected. Adepts do exist and are almost as common as Bards. Warmages, Beguilers and Dusk Blades are unknown. Warlocks are rare and distrusted. Artificers are anathema to the Tanolani.
While the Tanolani do make frequent use of potions and rarely use wands, they disaprove of permanent magic items and the Craft [Magic Arms And Armor, Rod, Wondrous Item, and Forge Ring] feats are unknown amoung them.
Skills:
Perception, Stealth and Survival skills are valued most highly by the average Tanolani. Craft (wood, leatherworking, cloth, basket weaving) are common. Craft (poison making) is not uncommon. Knowledge skills are rare outside of Knowledge Nature, and are mostly known by Bards or Experts.
Literacy is very rare amoung the Tanolani and only Druids and Bards should receive literacy for free for other classes follow the rules for Barbarians. If a class would normally get literacy at first level give the character a bonus language.
A Holy Site:
The grove of Legends seems to be an exception to the Tanolani disdain for permanence. In the sacred glen stands an irregular circle of great crystals. Each one is carved with glowing glyphs that tell the stories of the great legendary figures of Tanolani history. The druids explain that the crystals are living things, although none have yet withered and died, they are born to carry the cycle of legends. When a legendary figure arises amoung the Tanolani a new crystal grows in the grove to carry it's memory into future generations. The wisemen of the tribes then gather to decide who the stone has grown for, and then carve the legend into the crystals surface.
Races footnote: While most races work just fine as Tanolani Dwarves in this culture are very much breaking away from their racial stereotype of cave dwelling, stone carving, sword smiths. If you do want to put a group of dwarves in the culture consider replacing their Stone related racial abilities with something else. Alternately they could be a small clan that preserve the rarely used skills of stone carving for the rare time when a new Legend Crystal grows.