CustomBanMessage is a Bukkit/Spigot plugin that allows you to set a custom message that is displayed to a player when they are banned. The message is fully configurable in the config and this plugin is compatible with any banning system based on the Minecraft one (including Essentials). This is handy if you want players to know where they can appeal their ban or display other information to banned players.
You can download the latest copy from the BukkitDev page for this plugin: