Bukkit

WorldEdit is an in-game map editor for both creative and survival

WorldGuard

The most used authentication plugin for Spigot and CraftBukkit!

Grief Prevention

Open anyone's inventory as a chest in real time!

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

LoginSecurity

Stops people from breaking farmland

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

CoreProtect

Inexpensively protects your ores from cheaters.

Nerf those creepers

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

FastAsyncWorldEdit

Claim land of any shape, not just within a chunk

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

Detect and fight the exploitation of various flaws/bugs in Minecraft!

Lockette v1.4 - Simple chest and door lock, no databases!

SeePlayerInventory

Backup and restore your server with ease. [aupports FTP]