iCal is a calendar program for Mac operating system (it is included with the newer versions of Mac OS). The best feature of this program is its ability to import and manage external calendar sources, such as Google Calendar, Yahoo Calendar, and even Microsoft Exchange schedules. Your friends and colleagues may share their calendars with you so you know about important dates and events in their lives.
The user interface is very intuitive and looks like in most other calendar programs. Particularly, those who are used to Microsoft Outlook calendar will find this interface very familiar. Something that I found nifty is iCal's support of iPhone-like products. It means that all the important dates and events can always be with you (if you, of course, sync the program with your device) in your pocket or purse.
While reading up on this program, I found out that it has many reported bugs. Some major bugs include misfired alarms and inability to import some Google calendars. One of the biggest problems is when someone is traveling into a different time zone: all the events and the appointments are shifted in order to compensate for the time zone difference. My biggest disappointment came from iCal's inability to support vCalendars version 1. I have a birthday list made in version 1 that I now have to convert to version 2, so I can continue using Apple's iCal.
Overall, this program is made the Apple way - once you use it and get used to it, you can't imagine your life without it.