Exemplar

Exemplar is a prestige class found in Complete Adventurer. Exemplars are all about being really good at specific skills of the player's choice (or DMs choice if NPC). At fifth level they gain the ability to hold demonstrations (assuming it is non-hostile) of their chosen ability in place of Diplomacy checks and with enough levels in exemplar you eventually become so good at juggling or bookbinding that you become a magical creature.

Dungeons & Dragons 3rd Edition Classes
Player's Handbook:	Barbarian - Bard - Cleric - Druid - Fighter - Monk Paladin - Ranger - Rogue - Sorcerer - Wizard
Player's Handbook II:	Beguiler - Dragon Shaman - Duskblade - Knight
Complete Adventurer:	Exemplar - Ninja - Scout - Spellthief
Complete Arcane:	Warlock - Warmage - Wu jen
Complete Divine:	Favored Soul - Shugenja - Spirit Shaman
Complete Psionic:	Ardent - Divine Mind - Erudite - Lurk
Complete Warrior:	Hexblade - Samurai - Swashbuckler
Dragon Compendium:	Battle Dancer - Death Master - Jester Mounteback - Savant - Sha'ir - Urban Druid
Dragon Magazine:	Sha'ir - Deathwalker - Fleshcrafter - Soul Reaper
Dragon Magic:	Dragonfire Adept
Dungeonscape:	Factotum
Eberron Campaign Setting:	Artificer
Heroes of Horror:	Archivist - Dread Necromancer
Magic of Incarnum:	Incarnate - Soulborn - Totemist
Miniatures Handbook:	Favored Soul - Healer - Marshal - Warmage
Ghostwalk:	Eidolon (Eidoloncer)
Oriental Adventures:	Samurai - Shaman - Shugenja - Sohei - Wu jen
Psionics Handbook:	Psion - Psychic Warrior - Soulknife - Wilder
Tome of Battle:	Crusader - Swordsage - Warblade
Tome of Magic:	Binder - Shadowcaster - Truenamer
NPC Classes:	Adept - Aristocrat - Commoner - Expert - Magewright - Warrior
Class-related things:	Favored Class - Gestalt character - Multiclassing Prestige classes - Variant Classes - Epic Levels - Racial Paragon Classes