Bukkit

JCommandEssentials is the [Essentials, CommandBin, jCommands, ...] killer. It provides all the commands you can think of to manage a server.

Prevent players/groups from placing / breaking any specific block

Creative Item frame Control

Captain'sLog

McBansJocker

Verstecke deine Plugins! Hide your Plugins! Plugins, PluginHider, AntiPlugins, NoPlugins

Web interface for CoreProtect

A Simple Real Estate Plugin

Chunk based server backup and restoring plugin

A TNT and other block blocking plugin.

NoAccountHack

A Report Plugin for Bukkit

Allows people to sign in when server is full.

Define a rectangular border for each world. With the ignoreborders permission players will be able to go beyond the border.

Blocks TNT Ignition and placement for all users, notifies server operators

Libelula Protection Blocks

Prevent and notify actions from players without flood

Freeze a player in you server with a GUI system!

RealCops Reloaded

AntiPass is a plugin that picks up where NoCheat left off; it patches known NoCheat bypasses, and any new ones that will arise.