Due to the project that I'm working on now, a large open source software project, its helpful to know what time it is for each person. Due to time-zones, some people live in the future, where they are already living tomorrow, and some are living in the past. So it helps to know what time it is, so you'll adjust for when its a good time to send a quick message, or leave an overnight lengthy email. Or know to stay up a few more hours, or to be sure to make it in early.
Anyways, here are my tricks for keeping an eye on the time of your peers.
In Ubuntu, add the cities of your peers so you can see what time it is for them, and the weather, so you can make jokes about it.
As in, its summer in New Zealand and 60+ degrees, vs 20 and snowing in Columbus.
Plus you can check to see that they'll be coming online soon. In Ubuntu it has a nice world dark-ness overlay to see what everyone sees. And if you're cooped up in the office, to get out because its dark.
The other trick I like is in Gmail.
Its a labs feature called Sender Time Zone.
It shows what time it currently is for them, so you can know better than to just call someone, or to expect a response shortly.
It sits neatly next to their emails so you easily what that they're likely there or not.