iOS: If you know or work with people all over the world, it helps to know what time zone everyone is in. You can easily check different time zones on your phone, but OneTime lets you do this and more.

There are plenty of time-travel movies in existence, but most are either obtrusive "hard sci-fi" yawn-fests or patronising popcorn entertainment. Here are ten time-travel flicks that manage to successfully straddle the divide -- with trailers!

If you work with people in multiple time zones, it can be difficult figuring out what time it is where they live. If you need a hand, Windows has the tools you need built right in.

Worldtime Buddy is a webapp that not only displays the local time for multiple cities at once, but makes scheduling meetings worldwide easy by supplying a URL to a page showing how the meeting time will change across time zones.

Dear Lifehacker, For the most part, my phone and my laptop pick up automatically when I change time zones. But it seems like something always goes wrong, either in planning or on the spot, and I miss something important. What should I do to prevent future time zone mix-ups? Sincerely, Frequent Time Traveller

You're in Perth, but the rest of the team are back in the office in Sydney. Rather than schedule an important meeting during your lunch, you can use Google Calendar's new time zone support to ensure everybody knows the real start time.

If you're bad at keeping time-zone conversions straight, save yourself the embarrassment of a poorly timed phone call with a quick Google search.

Managing two or three time zones in your head should be easy, but the brain just doesn't seem to like living in more than one place. Every Time Zone helps make sense of the time and date anywhere in the world.

Windows only: Outlook Add-in Sender's Time Zone makes easy work of dealing with recipients in multiple time zones—no more calculating times in your head.