Bukkit

Save inventory and experience on death, implement death taxes, etc.

Multi-World capable Stargates for bukkit powered servers

PlayerBar

Multiworld management made easy

ItemCase

This plugin allows you to enable the pvp only at night in specific worlds! Very good for use in plots worlds!

Notifies people with the permission when someones mines ores.

The levelling up plugin; adding skills to Minecraft

An enchanting GUI for players to enchant their items easily.

ButtonLock

LethalSnow

UnCraft, UnSmelt, UnBrew, UnEnchant, and UnTrade to get your ingredients back!

Tree felling is easy when they pop like cacti

Catch the Power of Lightning !

Burn your ores with fire! Real fire!

Allows creating horse/boat/dragon routes

This plugin is still very new. But there are still some cool features! :)

MobLoot v4.0 [CB 1.2.3-R0.1]

Prevents players using/opening blocks/chests they can't see.

Full featured protection cuboid plugin with factions.