I work with people in a few different countries and I kept Googling "what time is it in Tokyo" before scheduling calls. Or worse, I'd forget and accidentally book something at 3am their time. Time Zoneish sits in your menu bar and shows the local time for your actual contacts. It pulls from your address book and calendar so you can see at a glance whether it's a reasonable hour to message someone. Simple idea, but it's saved me from a lot of awkward apology messages.