Display floating text. Thanks to http://www.youtube.com/watch?v=q1B19JvX5TE for the amazing trick. Uses PacketWrapper and ProtocolLib, but could be rewritten to avoid them.

DisplayFloatingText.java

package com.comphenix.example;

import org.bukkit.Location;
import org.bukkit.command.Command;
import org.bukkit.command.CommandSender;
import org.bukkit.entity.EntityType;
import org.bukkit.entity.Player;
import org.bukkit.event.Listener;
import org.bukkit.plugin.java.JavaPlugin;

import com.comphenix.protocol.wrappers.WrappedDataWatcher;

public class DisplayFloatingText extends JavaPlugin implements Listener {
    private static int entityId = Short.MAX_VALUE;

    private static final int WITHER_SKULL = 66;
    
    @Override
    public boolean onCommand(CommandSender sender, Command command, String label, String[] args) {
        if (sender instanceof Player) {
            Player player = (Player) sender;

            spawnNametag(player, player.getLocation(), 0.5, "Hello World");
        }
        return true;
    }

    public static void spawnNametag(Player p, Location loc, double dy,  String message) {
        WrapperPlayServerSpawnEntityLiving horse = new WrapperPlayServerSpawnEntityLiving();
        WrapperPlayServerSpawnEntity skull = new WrapperPlayServerSpawnEntity();
        WrapperPlayServerAttachEntity attach = new WrapperPlayServerAttachEntity();
        
        // Initialize horse packet
        horse.setEntityID(entityId++);
        horse.setType(EntityType.HORSE);
        setLocation(horse, dy, loc);

        WrappedDataWatcher wdw = new WrappedDataWatcher();
        wdw.setObject(10, message);
        wdw.setObject(11, (byte) 1);
        wdw.setObject(12, -1700000);
        horse.setMetadata(wdw);
        
        // Initialize skull packet
        skull.setEntityID(entityId++);
        skull.setType(WITHER_SKULL);
        setLocation(skull, dy, loc);

        // The horse is riding on the skull
        attach.setEntityId(horse.getEntityID());
        attach.setVehicleId(skull.getEntityID());
       
        horse.sendPacket(p);
        skull.sendPacket(p);
        attach.sendPacket(p);
    }
    
    private static void setLocation(WrapperPlayServerSpawnEntity living, double dy, Location location) {
        living.setX(location.getX());
        living.setY(location.getY() + dy + 55);
        living.setZ(location.getZ());
    }
    
    private static void setLocation(WrapperPlayServerSpawnEntityLiving living, double dy, Location location) {
        living.setX(location.getX());
        living.setY(location.getY() + dy + 55);
        living.setZ(location.getZ());
    }
}

How would I destroy the name plate that is created? Also, how would I save certain ones so they will stay after restarts?

Its so simple! Love it!!!! Keep up the great work!