This may have been suggested already, but an in-game clock (even if set to only one real-world time zone) would make managing play time much easier

You can type /time and it will display the time at UTC.

There's also a plugin that does this as part of the ToasterCrush Suite, voclock, but it has a few nasty bugs involving interface resizes (press F4)

+1 already requested, still a great option! (for those who have large screens, of course!)