Bukkit

Guilds, war, land claiming, and user-controlled antigrief

An advanced SQL based punishment management system for your server

a feature-rich world size limiting plugin, which can also generate or trim a world to your border

Player property protection using special block placement.

PlotSquared

Prism

Advanced /vanish plugin which makes other players think that you're not on the server

PreciousStones

CrazyLogin

Chunk protection plugin designed for ease-of-use.

Allows you to worldedit only in regions you own.

Hide from your players! Invisibility for the distinguished gentleman.

EntityManager

The premier long-range map editing tool for Minecraft SMP.

Residence

Continuation of the popular AntiCheat anti-cheating plugin.

stop fire spread, damage, and start with logging

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

A Lightweight plugin, that let's the user enable and disable griefing for certain mobs.

iSafe