Bukkit

NoPluginStealers

Plugin that logs player/IP combos and allows for a nice developer API to easily retrieve that data

Cutting trees is now so simple!

Allows chunk claiming using special terrain blocks.

Adds various treasures and surprise bags as mob drops

A basic plugin that adds essential functionality (oh and spleef :D)

TrollingFreedom | 70+ ultimate unique & funny trolls in a GUI | NEW COFFIN DANCE + CREEPER AW MAN

This plugin allows you to change your game mode with ease

Force players to use skins

A better version of BasicSpawn

Set up your own Block Scripts to do anything you want!

Adds /back command support

Gives rewards for advancements

Adds that RPG feel.

TacoAPI

Individual Messages

LDLogger logs a number of events on the server, and reports them to staff in chat.

This is a plugin like MinePlex, when a player joins, they will get a title and subtitle to greet them.

Papotronics

Tekkit ToolKit