Bukkit

PoleCompass is a simple lightweight plugin, where you can modify your compass to the max!

Stack any items, potions, water/lava buckets and more!

Inventory weight mechanic just like in RPGs!

CoolTime

Bukkit plugin version of the Minecraft mod CraftBack

Improves performance by tweaking mob despawn rules. Say bye to pesky unintentional persistent mobs.

Allows your players to combine/create their choice of potion effect(s) into ONE potion with a fee. Supports up to 14 effects in one potion.

Give items an enchantment that prevents dropping or moving the item.

Plugin with many radom pickers

SimpleGM - Change you gamemode with ease!

Fundy's Air Cannon item but as a plugin for your server!

Cook is a very simple plugin that cooks the item in hand.

EnderChest Command

Customize-able fancy scoreboard for your servers.

A plugin with everything you need to make your minecraft films better

Saves items dropped on death in a chest!

Have an Ultra customizable Chat Manager

Generates configurable mazes

ManHunt plugin from Dream's videos (even better)

A fast, reliable, and open source offline UUID and storage management API.