Do you frequently travel to other time zones or make appointments with those who do? If so, the mobile World Time Buddy app might be just what the doctor ordered. See it at…

http://www.worldtimebuddy.com/mobile-app

You can set several “favorite” time zones, see at a glance the way your appointments will stack up, note “dark” and “daylight” times in a flash, and much much more. It’s available both for iPhone and Android.