Bukkit

Simple plugin to prevent interaction with blocks and paintings.

This addon simply allows you to deny any interaction (inside regions) with blocks in config

A simple region based jail plugin.

An extensible, player-driven, chunk protection/ownership system.

BukkitProtect, protecting your worlds since it was made!

SimplyPerms

JailLikeHell- A simple jail plugin, with jail protection, and other features!

MCbb

Allows players to generate forcefields

We all know everyone wants that mcpvp spawn protection plugin. This plugin makes that possible! Made by MayoDwarf!

AutoRegionGuard

SmoothPlot - simple but powerful plots managment system - no pre-defined regions required - WorldGuard based

CrazyLoginFilter

Kingdoms 2

Login security to prevent player impostors.

Provides some level of control over the World Downloader mod.

Ban people/subnets/countries from "offline" servers

The extensible logging framework.

Protection system that protects each block individually

TurtleEconomy simplifies the Minecraft economy by only using 1 item as a currency.