Bukkit

MyBlock automagically protects user blocks from grief (placing, breaking, interacting) with minimal lag and a full feature set.

Lag-free world resets, anyone? If resetting is enabled, WR reverts you world folders from backups in a matter of seconds

Permits the use of redstone-based Geometric Magic

An easy, fast, custom way to set up your lobby or spawn

Adventcalendar generates an advent calender for you with many customizable options

Managing all the worlds. One at a time.

Allows users to create custom regions by just placing a single block

The world management plugin, which allows to manage zones, entity spawning, create frame-by-frame animations, manage world rules, the gates allows to teleport between places and worlds

GMNP

Manage your biomes

A plugin that allows easy use of explosions!

Makes snow more "real" and configurable.

Day/Night - PvP & Difficulty Cycle

Village and City Generator based on players position and radius.

CreativeStick will allow you to build, replace, or remove blocks at a distance by simply shaking a stick at them.

A lightweight plugin to load or generate a custom defined world

Introduce special items, SiBs, which turn into structures when placed by players

Kingdoms 2

A Plugin to Put a Password for System a command, such as /stop in case you Dont want to do them

ChunkUp, keeps chunks loaded.