Bellow is a list of where you can download the .pdf versions of the core rulebooks and supplementary sources for the 3.5 Edition of Dungeons and Dragons in alphabetic order.
Animated Series Handbook [XxX]
Arms and Equipment Guide (yeah, I know it's 3.0, but most of it is perfectly ok in 3.5 as well) [XxX]
Book of Exalted Deeds [XxX]
Book of Vile Darkness (technically 3.0, but mechanically more like 3.25) [XxX]
Cityscape [XxX]
Complete Adventurer [XxX]
Complete Arcane [XxX]
Complete Champion [XxX]
Complete Divine [XxX]
Complete Mage [XxX]
Complete Psionic [XxX]
Complete Scoundrel [XxX]
Complete Warrior [XxX]
Deities and Demigods (with 3.5 conversion booklet) [XxX]
Draconomicon [XxX]
Dragon Magic [XxX]
Drow of the Underdark [XxX]
Dungeon Master's Guide [XxX]
Dungeon Master's Guide II [XxX]
Dungeonscape [XxX]
Elder Evils [XxX]
Epic Level Handbook (with 3.5 conversion booklet) [XxX]
Expanded Psionics Handbook [XxX]
Fiend Folio (with 3.5 conversion booklet) [XxX]
Fiendish Codex I - Hordes of the Abyss [XxX]
Fiendish Codex II - Tyrants of the Nine Hells [XxX]
Frostburn [XxX]
Heroes of Battle [XxX]
Heroes of Horror [XxX]
Libris Mortis - The Book of Undead [XxX]
Lords of Madness [XxX]
Magic Item Compendium [XxX]
Magic of Incarnum [XxX]
Manual of the Planes (with 3.5 conversion booklet) [XxX]
Miniatures Handbook [XxX]
Monster Manual [XxX]
Monster Manual II (with 3.5 conversion booklet) [XxX]
Monster Manual III [XxX]
Monster Manual IV [XxX]
Monster Manual V [XxX]
Oriental Adventures (with 3.5 conversion from Dragon Magazine #31 cool [XxX]
Planar Handbook [XxX]
Player's Handbook [XxX]
Player's Handbook II [XxX]
Races of Destiny [XxX]
Races of Stone [XxX]
Races of the Dragon [XxX]
Races of the Wild [XxX]
Rules Compendium [XxX]
Sandstorm [XxX]
Savage Species [XxX]
Spell Compendium [XxX]
Stormwrack [XxX]
Tome of Battle - Book of Nine Swords [XxX]
Tome of Magic - Pact, Shadow, and Truename Magic [XxX]
Unearthed Arcana [XxX]
Weapons of Legacy [XxX]
