Time Zones.is a pretty cool site for working out what time it is in different timezones by just dragging a bar.  Another cool alternative is GMT Slider, which also has a cool widget that you can embed into you a website e.g. http://www.gmtslider.com/widget.jsp?id=aglnbXRzbGlkZXJyEQsSCUdNVFdpZGdldBi5iwQM