The World Clock – Time Zones is a great tool if you need to check time in other places. The starting page lists many but you can also create Personal World Clock with just the cities you need.

There is The World Clock Meeting Planner.

Need to make a call to someone far away? Need to arrange a videoconference, telephone- or net-based meeting with several people spread around the globe? This utility should help you find a convenient time, so that no one has to be up during the middle of the night.

Another tool is The Fixed Time World Clock.

Have you planned a web cast, online chat, teleconference call or other event where users from all over the world might participate? The Fixed Time World Clock can help tell your users when this event will happen in their local time zone

There is also Time Zone Converter, do time zone conversions between two cities.