World Clock 是一款Mac上实用的世界时钟，可以方便的添加世界各国的时钟，简单易用，还支持通知中心插件，很实用！
[World Clock 在 Mac App Store上售价30元]
Simple and powerful world clock:
• Add cities and timezones like GMT and UTC with a few key strokes.
• Convert international time with a drag of a cursor.
• Schedule international calls and meetings and add them to your calendar.
• Add Interactive Widget to your Today's View (OSX Yosemite only): quickly peek and see what time it is in the other location, drag the line to convert time, so you can find a time that suits quick, without getting distracted from whatever you were doing.