I've seen this on hey0 servers, and it seems like it would be pretty simple, but really helpful. Its where everyone once in a while, a TIP message comes up, giving a rule of the server or something like that. Example: TIP: Do not build single columns of blocks in the air. 5 mins later TIP: Please ask admins before clearing space to make a home. and so on...
Hey, I've built a plugin to achieve this, check it out ! http://forums.bukkit.org/threads/info-automessage-v1-0-display-automatic-messages.3022/
