Bukkit

Create custom recipes Crafting Tables, Furnaces, Smithing Tables, and more. Support for NBT and more

Your own Custom Mobs with everything you like

Keep your server running while mojang is offline, Supports all server versions!

Scriptable, interactive citizens.

Create scrollable command menus

EnchantmentAPI enables simple custom enchantment creation that behave like any vanilla enchantments!

OfflineManager - Manage offline players with commands!

VT or Skript like plugin allow you from shallow functionality to deep access to the server itself.

Fix your tekkit server's problems.

Utils and APIs: Config, Language and Inventory API, Protection Utils: WorldGuard, LWC, PlotSquared

A complete match and event framework for creating arenas and minigames in Minecraft. Supports creating modes through config files, or fully custom modes through plugins.

Websend

Easy prefixes and suffixes for in-game chat using permissions (Simple Prefix)

A continuation of the Log plugin to collect Modifications done by users

This does nothing on it's own and is a requirement for some of Tux2's plugins.

RaspberryJuice

qQuests - The simplest yet most customizable questing plugin since uQuest!

A fast cross-version particle API for Spigot and Bukkit server.

CompatNoCheatPlus

WorldGuard Custom Flags