This list from
http://www.geocities.com/Athens/7117/planes/abyss/abyss1.html is one of the more complete lists of the layers of the Abyss out there. However there is a massive amount of information about the Abyss on some of the Planescape websites such as mimir.net, ps3e.net, and of course the official 3e Planescape site
http://www.planewalker.com/.
PRIMARY WATERWAYS
River Styx
River Pyriphlegethon
LAYER 1: PLAIN OF INFINITE PORTALS (PAZUNIA, THE PALACE OF 1,001 CLOSETS)
IT: Battle Not With Monsters
IT: Broken Reach
IT: Edge of Sanity
IT: Mithrengo
IT: Gallowsgate
IT: Raazorforge (ITA)
IT: Sonu-Aar'ri
IT: Styros
Si: Lakes of Molten Iron
Si: Tower of Chiryn (WoW)
Si: Xaos Kult Kamp (formerly near Plague-Mort: details in SIGIS issue 12)
LAYER 2: "DRILLER'S HIVES"
LAYER 3: FORGOTTEN LAND
LAYER 4: GRAND ABYSS
LAYER 5: "WORMBLOOD" (I)
LAYER 6: REALM OF A MILLION EYES (Great Mother's realm)
RT: Failing Sight
LAYER 7: PHANTOM PLANE (KEARACKININ ) (Sess'inek's realm)
LAYER 8: "SKIN-SHEDDER" (I)
LAYER 9: BURNINGWATER (I)
LAYER 10: "THAT HELLHOLE" (I)
LAYER 11: MOLRAT (I)
LAYER 12: TWELVETREES
Si: Ship of Chaos (ITA)
LAYER 13: BLOOD TOR (Beshaba and Umberlee's realms; F&A)
Si: Gallowshill, the Fortress of Taramanda (Hellbound)
LAYER 14: A'SHAD'IFOHG
IT: A'Shad'Ifohg's Fall
Si: The Tower of Fangs
LAYER 15: THE COURTS OF MUSTERING
LAYER 16: THE ENDLESS GRAVEYARD
LAYER 17: THE WHISPERING LIGHTS (I)
LAYER 18: CARNAXIUS
Si: The Pyramid of Destruction
LAYER 19: FALSERAPTURE (I)
LAYER 20: CANDLESNUFF
LAYERS 21-22: unknown
LAYER 23: IRON WASTES (Kostchtchie's realm)
Si: Glacier Citadel
LAYERS 24-26: unknown
LAYER 27: MALIGNEBULA (Lissa'aere the Noxious' realm; Hellbound)
LAYER 28: THE MOUNTAINS OF MURDER
LAYER 29: unknown
LAYER 30: SLIMEFLOW
LAYER 31: DESERTS OF STILL SILVER (I)
LAYER 32: THE DUNGEON DIMENSIONS (I)
LAYER 33: HOLLOWSHELL (I)
LAYERS 34-36: unknown
LAYER 37: THE FEEDING REACH (I)
LAYERS 38-44: unknown
LAYERS 45, 46 AND 47: AZZAGRAT (TRIPLE REALM) (Graz'zt's realm)
RT: Argent Palace
RT: Zelatar
Si: Zrintor, the Viper Forest
Si: The River of Salt
RT: Samora
Si: The Counting House
LAYER 48: unknown
LAYER 49: THE HORRID SEA
IT: Sanspathos, the Lingering City
LAYERS 50-52: unknown
LAYER 53: IMPALATOR (THE GLASS SPIKES) (I) [*]
LAYERS 54-56: unknown
LAYER 57: TORTUOUS TRUTH (Duke Alvarez's realm; FoE)
LAYERS 58-61: unknown
LAYER 62: STING (Chask and Maughter's realms)
LAYER 63: CHITINOUS (Mantha's realm) (I) [#] [*]
LAYER 64: unknown
LAYER 65: LOLTH'S WEB
LAYER 66: THE DEMONWEB PITS (LOLTH'S WEB) (Lolth's realm)
LAYER 67: HEAVING HILLS
LAYER 68: UNNAMED (Void) (I)
LAYER 69: THE CRUSHING PLAIN (I)
LAYER 70: THE ICE FLOE (I)
LAYER 71: SPIRAC
LAYER 72: "DARKLIGHT" (I)
LAYER 73: THE WELLS OF DARKNESS (I)
LAYER 74: SMARAGD (Meershaulk and Ramenos' realms)
Re: The Viper Pit (Sseth's realm; P&P)
LAYERS 75-79: unknown
LAYER 80: "THAT MISERABLE PLACE" [*]
LAYERS 81-86: unknown
LAYER 87: SALT DESERT (The Balance Website, off-Mimir)
LAYER 88: THE GAPING MAW (Demogorgon's realm, formerly Yam's realm)
LAYER 89: DEMOZG
LAYERS 90-95: unknown
LAYER 96: NOGARD
LAYERS 97-99: unknown
LAYER 100: FORGE OF THE ABYSS [*]
LAYERS 101-111: unknown
LAYER 112: STALKINGBONES (FONT OF SKELETONS) (I) [*]
LAYER 113: THANATOS (THE BELLY OF DEATH) (Kiaransalee's realm, formerly Orcus' realm)
RT: Forbidden Citadel
RT: Naratyr, City of the Dead
RT: Lachrymosa, the Cauldron of Tears
LAYER 114: OPEN GRAVE (I)
LAYERS 115-120: unknown
LAYER 121: DEGRAZAZT
LAYER 122: FALSE FALLOW
LAYERS 123-127: unknown
LAYER 128: THE SLUGBED (Lupercio's realm; FoE)
LAYERS 129-141: unknown
LAYER 142: LIFEBANE (Chemosh's Realm, OHG)
LAYERS 143-155: unknown
LAYER 156: BOGGYWOOD [*]
IT: Abblerston
LAYERS 157-175: unknown
LAYER 176: HOLLOW'S HEART (Fraz-Urbluu's new realm; FoE)
LAYERS 177-180: unknown
LAYER 181: ROTTING PLAIN (Laogzed's realm)
LAYERS 182-192: unknown
LAYER 193: VULGAREA (Eshebala's realm; OHG)
LAYERS 194-220: unknown
LAYER 221: BLEKHOLE (I) [*]
LAYER 222: SHEDAKLAH (THE SLIME PITS) (I) (Jubilex's and Zuggtmoy's realms)
LAYER 223: OFFALMOUND (Moander's realm; abandoned; F&A; OHG)
LAYERS 224-240: unknown
LAYER 241: PALPITATIA (Grankhul's and Skiggaret's realms; OHG)
LAYERS 242-265: unknown
LAYER 266: ACID INDECISION (Tel'Quay's realm)
LAYERS 267-273: unknown
LAYER 274: DURAO (gateway layer)
Si: Gluttonous Depravity, the Citadel of Feasting
LAYERS 275-296: unknown
LAYER 297: THE SIGHING CLIFFS (Lynkhab's realm; FoE)
LAYERS 298-299: unknown
LAYER 300: FENG-TU (Tou Mu and Lu Yueh's realm)
RT: Feng-Tu, City of Disease and Madness
Si: Keui-Men-Kuan, Gate of the Demons
Si: How Nai-ho (river)
LAYERS 301-302: unknown
LAYER 303: SULFANORUM (smoking realm)
LAYERS 304-312: unknown
LAYER 313: UNNAMED
Si: Illssender's Tower (Hellbound)
LAYERS 314-323: unknown
LAYER 324: THEIVUKASH (Stromckkuk's realm) [#] [*]
LAYERS 325-332: unknown
LAYER 333: THE BROKEN SCALE (Hiddukel's realm; OHG)
LAYER 334: unknown
LAYERS 335-344: unknown
LAYER 345: FYERWOLD
LAYERS 346-347: unknown
LAYER 348: UNNAMED (Formerly Thralhavoc's realm)
Si: Taelec Mirrimbar, the Fortress of Indifference (Hellbound)
LAYERS 349-365: unknown
LAYER 366: AZGOROTH (I)
LAYERS 367-376: unknown
LAYER 377: PLAINS OF GALLENSHU (armanite realm)
RT: Blackmane (one of twenty-four stable-towns in the layer)
RT: Oxblood (also a stable-town)
RT: Amber
RT: Basalt
RT: Boneshard
RT: Clay
RT: Cold Iron
RT: Dark Spring
RT: Gray Glass
RT: Jade
RT: Mageblood
RT: Maroon
RT: Obsidian
RT: Ochre
RT: Purpure
RT: Silver Spike
RT: Steelshank
IT: Bleeding Head
LAYERS 378-380: unknown
LAYER 381: BODAK'S LAYER (The Balance Website, off-Mimir)
LAYERS 382-389: unknown
LAYER 390: THE HINGED PLAIN (THE CLAP) (I) [*]
LAYERS 391-398: unknown
LAYER 399: WORM REALM (Urdlen's realm)
LAYER 400: WOEFUL ESCARAND (nalfeshnee realm)
Si: The Mountain of Woe
Si: The Pits of Depair
LAYERS 401-402: unknown
LAYER 403: THE RAINLESS WASTE
IT: Mal Arundak, the City of Confusion (Fallen archon realm; FoE)
LAYERS 404-420: unknown
LAYER 421: SALTED WOUND
LAYER 422: THE SEEPING WOODS (YEENOGHU'S REALM) (Yeenoghu's realm)
LAYERS 423-428: unknown
LAYER 429: ANAGON (Realms of Anaroggg and Armon)
LAYER 430: FATAL BLEEDING (I) (The Balance Website, off-Mimir)
LAYER 431: CHAOTIC MEMORIES (I) (The Balance Website, off-Mimir)
LAYER 432: unknown
LAYER 433: ACID OCEAN (I) (The Balance Website, off-Mimir)
LAYER 434: SHRIEKING LANDS (HOUSE OF MASKS) (I) [*]
LAYERS 435-447: unknown
LAYER 448: THE GREAT BORDELLO (Syliviana's realm) [#] [*]
LATERS 449-461: unknown
LAYER 462: THE ATROCITY CAVERNS (I) [*]
Re: Maw of Atrocity (Aunkaatr's realm, abandoned, a dead god of the meazels)
LAYERS 463-470: unknown
LAYER 471: SUCCUBI WOMB (THE FLESH PITS) (I) [*]
LAYERS 472-486: unknown
LAYER 487: LAIR OF THE BEAST AND MANSION OF THE RAKE (Kanchelsis' realm; OHG)
RT: Feast Upon the Herd
LAYERS 488-498: unknown
LAYER 499: CARRORISTO (Hellbound)
Si: The Iron Fortress of Carroristo (Hellbound)
LAYER 500: VOLCANOES (The Balance Website, off-Mimir)
LAYERS 501-502: unknown
LAYER 503: TORREMOR (LAYER OF FLIES) (Pazrael's realm)
Si: Onstrakker's Nest
LAYERS 504-523: unknown
LAYER 524: SHATTERSTONE (Vaprak's realm, OHG)
LAYERS 525-529: unknown
LAYER 530: KAZUM, THE CITY OF THE PIT [*]
LAYER 531: THE ENDLESS TORTURE
Si: Planes of Pain
LAYERS 532-535: unknown
LAYERS 536: THE FAIR DECEPTION (SIGIS 17)
LAYERS 537-545: unknown
LAYER 546: THE NIGHTMARE CAGE (J'sald-Xerix's realm) [#] [*]
LAYERS 547-554: unknown
LAYER 555: MAGGOTLOCH (I) [*]
LAYERS 556-564: unknown
LAYERS 565: SANDSLIDE (THE FALLING DESERT) (I) [*]
LAYERS 566: BLOODFIELD [*]
LAYERS 567-574: unknown
LAYER 575: AWASH (I)
LAYERS 576-585: unknown
LAYER 586: PRISON OF THE MAD GOD (Diinkarazan's realm)
LAYERS 587-592: unknown
LAYER 593: PARCH
LAYER 594: THE MISTLANDS or EROTICA
LAYERS 595-599: unknown
LAYER 600: ENDLESS MAZE (Baphomet's realm, OHG)
Si: Pale Night's claw fortress (FoE)
LAYER 601: CONFLAGRATUM (Alzrius' realm, Hellbound)
LAYERS 602-612: unknown
LAYER 613: MORGONAUGH
IT: Ber-Gorgan
LAYERS 614-621: unknown
LAYER 622: ENGULFING ABOMINATION (I) [*]
LAYER 623: THE REALM OF CHAOS
Si: The Lake of Blood
Si: The Cathedral of the Damned
Si: Spires of the Arachnos
LAYERS 624-634: unknown
LAYER 635: BEHEMOTHOME [*]
LAYERS 636-641: unknown
LAYER 642: THE RED JUNGLE
LAYER 643: CAVERNS OF THE SKULL (I) (Kali's realm)
LAYERS 644-649: unknown
LAYER 650: THE TIMEPIECE INFERNAL
LAYERS 651-669: unknown
LAYER 670: THE CRUMBLING HELL (I) [*]
LAYERS 671-682: unknown
LAYER 683: TUTIOLTH (I)
LAYERS 684 and DOWN: unknown