One of the most tricky part of working with clients abroad is to give them the right time for a call or appointment.
When you setup an appointment with someone in a different time zone you have to get your calculations right to ensure that you give the right local time to the other person.
Every Time Zone is a perfect tool for that. You need to set the time according your preference and interactively the website lets you know the time zone in the other major timezones. For example the if I wanted to have an appointment on September 13, 2012 at 11 PM my time all I need to do is share this link http://everytimezone.com/#2012-9-13,660,6be and the other person will be able to see the local time of the appointment.
Simple but a neat idea.