Suppose you want to take the events on your desktop Mac and place them on your laptop for your next road trip. It's easy to transfer events, single calendars, or all your iCal calendars from one Mac (or account) to another. To make a copy of an event, just select the event in iCal and drag it to the Desktop, where it turns into a .ics file that can be opened with any application or Web service that supports the iCalendar format. To copy a calendar, select the calendar in iCal's Calendars column and choose File -> Export -> Export. The resulting sheet bears the name of the calendar (Home, for example). Click Export to save the copy. To export all your calendars choose File -> Export -> iCal Archive. The resulting .icbu file contains all of your iCal calendars, ready for you to import into another copy of iCal.
4. Remember to-dos
iCal users routinely create tasks with the program's To Do feature and then promptly forget to pay attention to them. If you need a gentle nudge to actually do something about a to-do item, select it, press Command-E, and in the window that appears, create an alarm for it. iCal's to-dos support the same kind of alarms offered for iCal events--Message, Message With Sound, Email, Open File, and Run Script. Although to-dos don't include a repeat option, you can create multiple alarms simply by clicking the subsequent Alarm entry that appears after you create the initial alarm.
5. E-mail an event no matter what your e-mail client
iCal has a helpful feature that lets you e-mail someone else an event. To do so, just Control-click (or right-click) on an event and choose Mail Event. Regrettably, this feature uses Apple's Mail application, regardless of the e-mail client you may have configured as the default.
If you use a different e-mail client such as Microsoft Entourage, Qualcomm's Eudora, or Stickshift Software's Mailsmith, you're almost out of luck. You'd be completely out of luck if not for ZappTek's free iCal E-mail Notifications. These AppleScripts force iCal to choose a different e-mail client (supported clients include Entourage, Eudora, Mailsmith, CTM Development's PowerMail, and GyazSquare's GyazMail). Although the ZappTek site makes no mention of Snow Leopard, the Leopard scripts appear to work with Snow Leopard's version of iCal.