Clocker - Keep track of people in different time zones
Fantastical 2 - Fantastical, the Mac calendar app you'll enjoy using. Quickly create new events with natural language input and more.
World Clock iOS 8 Widget - Check the time, anytime. Just pull down Notification Center.
Microsoft Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
Dato - Better menu bar clock with calendar and time zones
Morgen.so - All-in-one Calendar, Tasks & Scheduler. Morgen is the single hub for everything that revolves around time management.