D20 Modern and Urban Arcana will serve as a basis for the advanced classes in UP. Beyond that...that's what you fine folks are for 
Here are the Advanced Classes from D20 Modern, including 4 FX classes:
-Soldier
-Martial Artist
-Gunslinger
-Infiltrator
-Daredevil
-Bodyguard
-Field Scientist
-Techie
-Field Medic
-Investigator
-Personality
-Negotiator
-Telepath
-Battle Mind
-Mage
-Acolyte
From what I remember from Urban Arcana (If I left anything out, feel free to let me know)
-Archaic Weaponmaster
-Mystic
-Shadow Hunter
-Swashbuckler
-Technomage
-Shadow Jack
-Speed Demon
-Thrasher
-Wild Lord
-...grr, can't remember the rest!
Note-please check out the rules change thread for an explanation of Advanced Classes (Link)
Also in Urban Arcana:
Arcane Arranger
Glamorist
Street Warrior
Prestige Classes:
Archmage
Artificer
Ecchlesiarch
Holy/Unholy Knight
In Urban Arcana web enhancement:
Mastermind
Shapeshifter
SpecOp
Sniper
Spellslinger
In d20 Future:
Ambassador
Dogfighter (largely irrelevant in Planescape, unless you plan on adding in starships on some of the void-like planes, like Air, the Astral, Vacuum, most of the Prime, etc.)
Dreadnought
Engineer
Explorer
Feild Officer
Helix Warrior
Space Monkey
Swindler
Technosavant
Tracer
Xenophile
Mecha Jockey
The Techie was largely rendered redundant after the release of d20 Future, thanks to the rules for constructing robots and the Mastercrafter feat. However, two classes replace it in role: the Technosavant and the Engineer.