Bukkit

Easy to use in-game sign editor

Command Signs

Remove lag and improve the performance of your server significantly with this tool!

Play Custom sounds when a player joins/leaves/talks/dies or respawns

Get custom items on join.

Add functioning stats to your items to allow players to increase their player stats.

Lets ops keep tallys on servers

SimpleClans

CraftBook adds a number of original gameplay elements to Minecraft from integrated circuits to gates

Change your Serverlist Motd! (WITH PLAYERNAMES)

Logs chat and commands

Automatically have player ranks change depending on how long they have been online.

This plugin allows you announce/send Actionbar as message or on join/firstjoin (also ANIMATED ACTIONBAR)

Automatic Announcements

Hub - Plugin

LogBlock

Show a picture of your player's head in chat when they join! Very configurable.

Administrate your server with ease!

Best MOTD plugin, that will make ur server look SEXY!

Join Message Plus allows you to change or turn off the join and quit messages of Minecraft.