Bukkit

Skyoconomy plugin by Skyost

For a Server Setting view or edit Data Control

ItemCommand

A plugin that allows developers to completely hide a player's nametags.

Version independent API to Execute whole lines of craftbukkit code at once!

Experiment with disguises!

SLSJoin

Guides provides a guide-system for different Plugins.

An API for writing plugins in Scala.

Adds user interfaces features (an inventory-menu, noteboard, and message system) for use with other plugins.

Allows the creation of multiple scoreboards and iterate thru them. Also allows the modification of scoreboards via console

MySQL API for developers who don't have the time to bother with databases.

Plugin Tweaks

A plugin developer tool to allow you to create custom popup menu systems for vanilla minecraft players using an API

This plugin allows you to keep your plugins up to date.

Plugin for Minecraft Spigot which allows teleporting through the dimensions (especially for using with JourneyMap)

Simple Plugin Management for those wanting to reload enable and disable individual plugins (or all)

The easiest way to create new mods

Allows you (and further developers) to apply Attributes to ItemStacks

Safe Trading between 2 players