How do you add in things like announcements or a tip system that echo through the whole mud. I have seen some muds that have a tip system that randomly scrolls a different tip at a desired time in the game.
Quick overview which in essense should work in any stock Diku derivative.
Two parts, the bit that does stuff...
Create a function to perform the echo, either using a CHAR_DATA* to run through the character list and echo to the players based on thier config, or you could just send_to_all() (or you have it or equiv) to echo out to everyone regardless. Exactly how this works (random selection of a tip or whatever, or more specific announcements) is something you have to decide for yourself.
.. and the bit that does it periodically...
In update.c create yourself a new pulse timer section (or choose an existing one, creating a new one based on whats there already shouldn't be hard) based on the frequency of the echo's you want to produce (PULSE_TICK or whatever they are called for you). Inside this block you want to call the function you wrote to perform the output.
I have a few other ways to doing this, but those changes require a rather significant adjustment to the internals of the system, so I'll leave them well alone