Bukkit

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

Write Bukkit plugins using Ruby

TeamSpeak

DiaHub

This API makes it possible for you to check whether a Twitch Stream is online or offline.

Ultimate Customization Plugin fully controllable via GUI's w/ Script System

Creates a config per-player.

Creative, but Limited to be used by Staff on servers and not be able to abuse!

This plugin allows you to manage your server plugins

Simply change/stop the time and change the weather in seconds!

Connect to your server from a website and send commands and get information.

Automatically teleports a player to spawn at login.

YouControl v1.0 - The easy to use Spout GUI for Admins.

The best way to write Javascript plugins.

INFOPLAYERS

Wide Library to simplify plugin creation process.

minesignss

Groovy Loader

OPMC (OPMessage/OPControl)

All in One Server Administration Tool