Filidh
Filidh, also spelled as Filí, were an elite caste of historian-poets in Irish Celtic society, and it is from their oral traditions that much of what we know about the Irish Celtic society was passed down to us, though like their Druid counterparts they eventually lost the battle for social status against Christian priests and faded away, though they did at least do better in passing their tales and stories on to the Irish monks and thus more about them was passed down to us.
In Dragon Magazine #324, the Filidh is offered as a class for Dungeons & Dragons 3rd Edition, specifically being described as an elite caste of judges, lawkeepers and enforcers within barbarian civilizations. As the article puts it: "if shamans are the conscience of the tribe and skalds its memory, then filidhs are its unshakable will". They strive to both enforce and protect ancestral traditions, and so often become adventurers to increase their knowledge and power. Divination magic is key to their role, but so are the more traditionally explosive spells of the wizard, and they often play subtle but domineering roles in any group they join. They are frequently on relatively good terms with druids or other religious orders, and tend to be quite religious compared to wizards from other cultures, usually revering creator gods as well as gods of nature, secrets, knowledge, magic, poetry and travel.
Mechanically, a filidh is a wizard who sacrifices all of the wizard class features (namely the Familiar) apart from spellcasting for the Filidh Knowledge and Greater Divining features. They also have a unique class skills list (Concentration, Craft, Decipher Script, Gather Information, Intimidate, Knowledge (All), Sense Motive, Spellcraft, and Survival) and weapon/armor proficiencies (club, dagger, quarterstaff and shortbow).
Filidh Knowledge is literally just Bardic Knowledge with a new name, and the two features stack if the filidh multiclasses as a bard.
Greater Divining gives the filidh a +1 caster level bonus with Divination spells per 5 levels of filidh they have - so +1 at filidh level 5, +2 at 10th, +3 at 15th, +4 at 20th, etc.