Prestige class

A prestige class is a narrow focus class with particular entry requirements that develops a campaign-specific element. Prestige classes are optional and totally in the purview of the Dungeon Master.

Zach Shuford's Kriegstanz:

http://www.kriegstanz.com/

"Fractious Factions" web enhancements:

http://planehopping.tripod.com/287.html

Planewalker.com:

/ps3e/prclass.php

Revolutionary League

Arcane Arranger (Urban Arcana, in the d20 modern SRD)

Anarchomancer (Dragon #315)

Glamourist (Urban Arcana)

Street Warrrior (Urban Arcana)

Epic Infiltrator (Epic Level Handbook)

Bleak Cabal

Alienist (Complete Arcane)

Chaositechnician (Xaositect)

Athar

Disaffected (Requiem For A God)

Defiant (Planar Handbook)

Athar (Dragon #287)

Necrotheologist (Requiem For A God)

Threnody (Requiem For A God)

Havester of Divinity (Requiem For A God)

Ur-Priest (Book of Vile Darkness)

Diabolist (Book of Vile Darkness, only those Athar who have decided the forces of Hell are preferable to the false Powers)

Cosmosopher (Aasimar & Tiefling: A Guidebook to the Planetouched)

High Proselytizer (Epic Level Handbook)

Doomguard

Warrior of Darkness (Book of Vile Darkness)

Doomlord (Planar Handbook)

Cancer Mage (Book of Vile Darkness)

Soul Eater (Book of Vile Darkness)

Ruin Priest (When the Sky Falls)

Necrotheologist (Requiem For A God)

Chaositechnician (Chaositech)

Machine Mage (Chaositech)

Sinker (Dragon #287)

Defiler (Dragon #315)

Dustmen

Necrotheologist (Requiem For A God)

Threnody (Requiem For A God)

Pale Master

True Necromancer

Companion of the Dead (Dragon #315)

[half-undead races in Dragon #313]

Believers of the Source

Osteomancer (Dragon #317)

Flux Adept (Dragon #317)

Celestial Mystic (Book of Exalted Deeds)

Seeker of the Song (Complete Arcane)

Visionary Seeker (Planar Handbook)

Transcendent Order

Speed Demon (Urban Arcana)

Cipher (Dragon #287)

Cipher Adept (Planar Handbook)

Kensai (Oriental Adventures, Complete Warrior)

Xen Chi mystic (Aasimar & Tiefling)

Perfected One (Dragon #297)

Swashbuckler (Urban Arcana)

Fated

Mindbender (Complete Arcane)

Fatemaker (Planar Handbook)

Taker (Dragon #287)

Guardians

Avatar (Avatar's Handbook)

Lion of Talisid (Book of Exalted Deeds)

Sentinel of Bharrai (Book of Exalted Deeds)

Stalker of Kharash (Book of Exalted Deeds)

Wonderworker (Book of Exalted Deeds)

Order of the Planes-Militant/Sons of Mercy

Avatar (Avatar's handbook)

Celestial Mystic (Book of Exalted Deeds)

Defender of Sealtiel (Book of Exalted Deeds)

Emissary of Barachiel (Book of Exalted Deeds)

Exalted Arcanist (Book of Exalted Deeds)

Fist of Raziel (Book of Exalted Deeds)

Initiate of Pistis Sophia (Book of Exalted Deeds)

Prophet of Erathaol (Book of Exalted Deeds)

Slayer of Domiel (Book of Exalted Deeds)

Sword of Righteousness (Book of Exalted Deeds)

Vassal of Bahamut (Book of Exalted Deeds)

Church Inquisitor (Complete Divine)

Silverhair Knight (Dragon #315)

Harmonium

Church Inquisitor (Complete Divine)

Knight Protector (Complete Warrior)

Harmonium Peacekeeper (Dragon #315)

Guardian Paramount (Epic Level Handbook)

High Proselytizer (Epic Level Handbook)

Union Sentinel (Epic Level Handbook)

Fraternity of Order

The Master of the Secret Sound (Dragon #297)

Necrotheologist (Requiem For A God)

Technomage (Urban Arcana)

Archivist (Heroes of Horror)

Cosmic Descryer (Epic Level Handbook)

Loremaster (DMG)

Sodkillers

Order's Tyrant (Unholy Warrior's Handbook)

Acolyte of the Skin (Complete Arcane)

Agent Retriever (Epic Level Handbook)

Vengence Knight (Champions of Ruin)

Xaositect

Fatespinner (Complete Arcane)

Wild Mage (Complete Arcane)

Drunken Master (Complete Warrior)

Chaotician (Planar Handbook)

Jester (Dragon #330)

Xaositect (Dragon #287)

Free League

Ronin (Complete Warrior)

Society of Sensation

Ardent Dilettante (Planar Handbook)

Sensate (Dragon #287)

Vile Hunt

Black Blood Cultist (Champions of Ruin)