Sound is a huge part of what brings immersion into a game, and I feel Minecraft lacks this in some places. BetterSounds adds sound to actions within the game where it doesn't usually exist. This includes things such as crafting and combat.
Drag and drop BetterSounds.jar into your servers plugin directory.
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As of now, BetterSounds is fairly limited in what sounds it currently adds to the game. I plan on adding a ton of more sounds to other actions, as well as adding more 'precise' sound effects.