So I had this idea. I get them sometimes.
You know how when you're talking to somebody from another country using IM, i.e. AIM, MSN, ICQ, Y!M, IRC, or other crazy stuff, and because you're in different time zones you end up in endless discussions of what time it is for each person? And how it's worse when there's more than two people in the room, all wanting to make sure everybody know what time it is? That stuff? I figured out how to fix it.
You add an option to your settings screen where a user can specify his or her time zone. By default, the client would read this directly from your system settings though obviously you would be able to override it. Then, in any conversation, a small message appears at the top right which depicts the current time for you, the current time for them, and if necessary the current time for everybody else in the room.
That's it. Makes sense, doesn't it? Now go implement it, people! And happy Lent-End.