Bukkit

NBTEditor allows easy customization of entities and spawners. It also provides tools to manage other NBT related objects.

RideThaDragon

Doors made out of blocks - from the ol'skewl HeyO mod

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

Bukkit plugin that allows smelting armor and tools into raw materials.

MorePhysics

GUI based bounty system with Placeholders and MySQL

Player changed their name? Don't know who they are? Try WhoWas!

Buddies Plugin

GrenadeCraft: Plugin for CraftBukkit, which allows you to throw different Grenades (Eggs, Snowballs, etc.)

All in one police plugin!

Add wishing wells to Minecraft, which may return rewards!

A simple party plugin for use with SkillAPI that allows for shared experience

Automatic inventory management for all your players! Defeat the tedium of manual organization! AutomaticInventory

Kill the Bat

Adds new crafting recipes to your Minecraft Server

Brings magic into the world of Minecraft with spells and items

Bring Skyrim to Bukkit!

RegionShop uses WorldGuard Regions to create shops.

It's for managing your plugins and install and update new ones.