Many MUDs use a "tick counter" to inform players about time flow (tick == in-game hour, usually). It would be nice to have a countdown box visible somewhere conveniently - below inputbar, top right corner of the mud window - I don't really care where, put it wherever it fits best your design ideas.
The important thing is for it to be accessible via scripting interface, so triggers can be set up to sync the counter.
An extension to this idea is to be able to create arbitrary counters, with or without visible countdowns, for various scripting purposes.
Thanks for your time.