Books Checked
DMG, PHB, MM
Complete Arcane, Warrior, Divine, Adventurer
Libris Mortis
Heroes of Battle
Sandstorm
Races of Destiny, Races of Stone, Races of the Dragon
Draconomicon, Dragon Magic
Lords of Madness
Book of Exalted Deeds, Book of Vile Darkness
Eberron Campaign Setting, Magic of Eberron, Races of Eberron, Players Guide to Eberron, Faiths of Ebeeron, Five Nations
Prestige Classes
Some of these have more obvious entry requirements than others. Things listed as "any" I think really could be managed by "any" class, but it may have some serious pre-reqs. An example would be the "XXX Initiate" feats from the ECS which require summon nature's ally ... this typically only appears on the Druid list but if you added that spell to your list via another means (Recaster, for instance) you could concievably add this to just about any arcane caster (Warmage, for instance).
Prestige Classes
Book of Exalted Deeds - Celestial Mystic
- Gains Celestial spells
Magic of Eberron - Impure Prince
- Expanded spell list
Heroes of Battle - Combat Medic
- Can lose spells to spontaneously cast heal even if it isn't on your spell list
- not really added to your spell list
Races of Destiny - Loredelver
- Can lose spells to spontaneously cast knock, arcane eye, greater dispel magic
- not really added to your spell list
Races of Stone - Shadowcraft Mage
- Can mimic any wiz/sorc evocation and most conjuratoin spells
- not really added to your spell list
Heroes of Horror - Fiend Blooded
- technically requires arcane casting to get in, but can advance either
Complete Arcane - Blood Magus
- Adds death knell
Complete Arcane - Geometer
- Adds glyph of warding / greater glyph of warding
Complete Arcane - Mage of the Arcane Order- Prc
- Spell pool (new spell ability specifically mentions not being useful for spontaneous casters)
Complete Arcane - Sublime Chord
- Has a merged Bard/Sorc/Wiz list for 4th level and higher spells
Complete Divine - Rainbow Servant
- Adds air, good and law domains
- Grants clerical spell access (and according to the FAQ this means all of them for the Beguilers, Dread Necros, Warmages, etc. out there)
Book of Exalted Deeds - Exalted Arcanist
- Add exalted spells to your spell list
Book of Exalted Deeds - Troubador of the Stars
- Add sanctified spells to your spell list
Five Nations - Silver Pyromancer
- Adds Paladin spells
Races of Eberron - Recaster
- Changeling
- Has two Expanded Knoweldge abilities - each allows the Recaster to add ANY spell from ANY spell list
Races of the Dragon - Dracolexi
- Adds extra spells known, including power-word spells
Sandstorm - Sand Shaper
- Enhanced spell list
Complete Mage - Lyric Thaumaturge
- Adds sorc/wiz spells to your bard list at 3rd, 6th and 9th level.
Complete Mage - Unseen Seer
- Adds divination spell from any class list to yours at 2nd, 5th and 8th
Dragon Magic - Wyrm Wizard
- Adds a spell from any class list to yours at even levels
Frostburn - Frost Mage
- Adds a small number of spells to your class list (conjure ice beast, etc.)
Complete Divine - Church Inquisitor
- Adds the inquisition domain
Complete Divine - Contemplative
- Adds domains
Complete Divine - Divine Oracle
- Adds the oracle domain
Complete Divine - Radiant Servant
- Adds a bonus domain (glory or purification)
Complete Divine - Sacred Exorcist
- Adds a bonus domain domain
Complete Divine - Seeker of the Misty Isle
- Adds the travel and magic domains
Draconomicon - Dracolyte
- Adds glory or domination domain
Dragon Magazine 280 - Eldrich Master
- Adds spells but does not advance casting. Instead adds bonus slots.
Dragon Magic - Swift Wing
- Adds the dragon domain
Faiths of Eberron - Sovereign Speaker
- Adds 9 domains over time
Forgotten Realms' Campaign Setting (p.47) - Hathran
- Adds a few spells
Lost Empires of Faerun - Olin Gisir
- Olin Gisir gets dispel evil, dispel chaos or dispel law at lvl4 and dictum, holy word or word of chaos at lvl8 added to her spell list
Masters of the Wild - Hexer
- Adds several Sorc/Wiz spells to their spell list over the course of 10 levels
Unearthed Arcana - Prestige bard, paladin & ranger
- Adds base class list
Waterdeep? - Guild Wizard
- Adds Break Enchantment as a 4th level spell
Feats
Champions of Valor - Sword of the Arcane Order
- Prepare wizard spells from spellbook into paladin slots
Complete Arcane - Draconic Legacy
- Add set of spells to your list based on your Draconic Heritage
- The first Draconic Heritage feat requires Sorc 1st, but the Legacy feat doesn't MANDATE that you add the spells to Sorcerer class (but I think that would be the most common assumption)
Complete Arcane - Extra Spell
- Add a spell to your list of known / available spells
- can only add class spells to your list of known
Complete Divine - Arcane Disciple
- Add one domain of spells to your class spell list
Dragon Magazine #325 - Customize Domain
- Pillage any list meeting various requirements for your domains. Your 5th level Cloistered Cleric with the Travel and Luck domains just got way stronger.
Dragon Magazine #330 - Cerebrosis
- Adds 11 spells with a far realms feel.
Dragon Magazine Compendium - Bloodline feats (various)
- Add spells. Some have drawbacks
Player's Handbook II - Celestial Sorcerer Heritage
- Adds protection from evil ... SORCERER ONLY
Player's Handbook II - Celestial Sorcerer Lore
- Adds magic circle against evil, tongus & teleport ... SORCERER ONLY
VARIOUS - Initiate Feats
- Adds a list of spells, typically to a divine list
Libris Mortis - Mother Cyst
- Add Cyst spells
Heroes of Horror - Corrupt Arcana
- allows spontaneous casters to prepare corrupt spells the same way that a wizard or cleric would (and they don't count against your total spells known)
Heroes of Horror - Improved Oneiromancy
- adds a number of dream-related spells to your list (requires two feats prior)
Alternate Class Features
By Class
These are additions that are truly only available to a single class.
Beguiler
Players Handbook 2
- Advanced Learning class feature at levels adds wiz/sorc enchantment or illusion spell to the list
Cleric
Complete Mage
- Lose one domain, add one abjuraction, divination or necromancy spell to your list for each new spell-level you can cast
Favored Soul
Dragon Magic - Favored of Bahamut/Tiamat
- Adds two sorcerer spells (one 1st level at 3rd, one at 12th level)
Paladin
Five Nations - Bone Knight
- If your divine spellcasting class was paladin, you add a subset of spells to your Paladin list.
Sorcerer
Races of the Dragon - Dragonblood Racial Substitution Level
- Adds spells to your list based on alignment
Complete Champion - Domain Access
- Add a domain to your sorc list (lose 1/spell each level)
Warmage
Complete Arcane
- Advanced Learning at specific levels can add wiz/sorc invocation/evocation spell to the list
Players Handbook 2 - Warmage Class
- Eclectic Learning option (replaces Advanced Learning) can add ANY wiz/sorc sepll to the list; treated as one level higher (so a cantrip would be added as 1st level spell, etc.)
Wizard
Unearthed Arcana - Domain wizard
By Race:
Dragons of Eberron - Soveriegn Archtypes
- True dragons may gain cleric or druid lists, often with little or no downside.
Items
Items
Magic Item Compendium - Runestaves - Item
- allows an arcane caster to expend a slot to cast the spell in the staff. See also Raiment of the Four Set: Magic Missile (Gloves of the Starry Sky, MIC 204), Teleport (Belt of the Wide Earth, MIC 204), Fireball (DC 14 RAW) (Goggles of the Golden Sun, MIC 205), Freedom of Movement (Periapt of the Sullen Sea, MIC 205)
Vestments of Divinity Set: Divine Favor (Cord of Favor, MIC 215), Death Ward (Phylactery of Virtue, MIC 215)
Complete Champion - Domain Staff - Item
- allows a divine caster to expend a slot to cast the spell in the staff
Complete Arcane - Ring of Theurgy - Item
- Spells stored in ring are treated as on your class list (but disappear when cast)
Magic of Eberron - Spellwurm - Item
- Symbiont; adds blur, ancient knowledge and mage armor
Explorers Handbook - Drake Helm - Item
- Can attune spells to the helm; act as if they are on your known-spells list
Dragon Magazine - Knowstones - Item
- As above but more modular and a better buy.
Non-standard means
Other
Complete Mage - Boccob's Reading Room (Magical Location)
- Allows a character who prepares spells to write a new spell into their spellbook
Special Mention
Dragon blood spell pact –(Dragons of Faerun)
http://www.wizards.com/default.asp?x=dnd/frcc/20070606 Godsblood Spellthief
Prerequisites: Steal Spell as a class ability.
Benefits: Select a domain from one of the deities involved in the Time of Troubles on the following list:
Anhur, Bane, Bhaal, Clangeddin Silverbeard, Gilgeam, Gond, Gwaeron Windstrom, Hoar, Ibrandul, Iyachtu Xvim, Kelemvor, Labelas Enoreth, Leira, Malar, Mask, Myrkul, Mystra, Nobanion, Ramman, Red Knight, Selune, Shar, Shaundakul, Tiamat, Torm, Tymora.
When you steal a spell, you can use the stolen spell energy to cast a single spell from the domain you have chosen. The domain spell must be of equal or lower level than the spell you have stolen. If you do not cast this spell within one hour, the spell energy fades away harmlessly. You can select the good, evil, chaos, or law domain only if that domain does not conflict with your alignment. You can use this feat a number of times per day equal to your Charisma modifier. This ability functions in all other ways like the Steal Spell ability.
Special: This feat can only be selected once.