Maphacks
Maphacks reveal the entire act so one can see where everything is, including dungeons and any entrances to other areas. Players tend to use maphacks online; undetectable maphacks are available to use on battle.net, but Blizzard is against using them and will ban the account of any player detected using one. Maphacks are a use-at-your-own-risk type of program.
Inventory Editors
There are hacks to alter a character's inventory in the form of INI files that someone can edit and create items to inject into the game. A little complicated to some, trainers can make character editing much easier and user-friendly.
Character Trainer
Editors can change all aspects of a single-player or open battle.net character, such as inventory items, all stats, quests and name. Programs like this give you full control of what characters will be like when saved and entered into "Diablo II." Character editors can ruin a single-player character and corrupt the files, so be wary when using these types of programs.