The Diablo 2 Wiki
The Diablo 2 Wiki archive is available for anyone looking for information on Diablo 2. All information here is pre-D2R but contains a lot of useful information that is still relevant. Updated sections for new D2R features can be found on the PureDiablo Diablo 2 section

Category:Item Generation

Category page
Diablo II Items [e]
Weapons
AxesBowsCrossbowsDaggersJavelinsMacesPolearmsSceptersSpearsStavesSwordsThrowingWands
Armor
BeltsBody ArmorBootsCircletsGlovesHelmsShields
Class-specific
Assassin ItemsAmazon ItemsBarbarian ItemsDruid ItemsNecromancer ItemsPaladin ItemsSorceress Items
Other
CharmsClass ItemsCraftedHoradric CubeRunesSet ItemsUniquesJewelsSockets
Guides and Stats
CalculationsGamblingItem GenerationModifiersRunewordsQuest ItemsPotionsEtherealGemsBase Item LevelsMisc

The mechanics Diablo II uses to generate items are complicated, detailed, and frequently unintuitive. Happily, they can be understood with some study, or failing that, you can just look at lists to see what drops where, without much caring why (or why not). The pages in this section should help you achieve that goal.