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.
That's right, like many other things out there, Google provides OneBox results for local times. Just type something like time [city|state|country]into Google, and Google will give you a OneBox result of the local time at that location. We've featured other time-zone tools in the past and even mentioned Google's time zone tool in passing, but after checking out a different time-zone converter (via One Thing Well), we figured Google's OneBox shortcut is handy enough that it deserves an individual callout.
For a more elegant look at time zone conversion, check out previously mentioned Every Time Zone. Gmail users, you may want to turn on the Sender time zone Labs feature for a little extra time-zone help.