Bukkit

Mine spawners with silk touch

Allows server admins to easily modify how Minecraft works without programming anything

A simple to use and powerful plugin to create user interfaces.

Creates images and pixel-art using in-game blocks

**Not Maintained** Display an RPG-style health bar above mobs and players.

Slimefun

The best chest&sign shop system for Bukkit

Easily add commands to NPC's! [1.8-1.12] (BungeeCord Support | Citizens 2)

Addeds the Ability to play music from a custom resourcepack on a server, without overriding existing music

Grief Prevention

An mcMMO themed plugin for horse role-playing.

Claim land of any shape, not just within a chunk

A simple and powerful backpack plugin with SQLite and MySQL storage.

Have minecraft read the chat to you

BackAgain

Limits amount of creater spawns via limits set by config

LimitDrops

Lets you sell a players heads for half of their money

Fully customize any mobs (and create custom mobs) with a powerful scripting skill system, attributes, equipment, special AI, and much more, along with custom spawners and spawning rules. The ultimate plugin for making RPG servers and minigames.

Players in creative can 1-hit-kill mobs when crouching