There’s lots, but just like everything, very few people actually can stick with and use them. Probably the thing that I think would be a logical feature in most chat programs, would be if say you put in your timezone into the client somewhere, then when you type a time you put some character before it like *3:30pm - the chat client could determine your timezone, put it in chat as UTC, and each recieving client could automatically convert it to their users timezone (and I suppose some kind of tag to make it so people know it is already translated to their timezone).