I've just got out from a meeting and after a colleague happened to display their calendar on the projector noticed something which (for me at least) is really dead useful. I never knew you could display more than one timezone on your Outlook calendar simultaneously. I regularly have online meetings with people based over in Seattle, and although I know they are always 8 hours out from me, this is a bit of a no-brainer option to make things even more obvious.
Open up the calendar in Outlook (BTW did you know the keyboard shortcut Control-2 does this too - I use it all the time), right click above the time column and select Change Time Zone. Provide a label for your current timezone (GMT in my case), and add a second timezone (PST is the most appropriate for me).
Click OK, and Outlook looks like this.
Love it. Sooo simple.