I've been getting into iCal a lot lately. I like having different calendars so I can see things together if necessary, or just one part of my life at a time.
I really like the way it ties to everything else on my Mac. Birthdays can be brought up from Address book, I'm sure there's a way to send meeting requests because iCal keeps automatically picking up requests from Outlook when people send them to me.
I like to subscribe to other people's calendars and I even publish a few of my own for friends in online communities of similar interests. Want a daily-updated New York Islanders schedule?
Subscribe to my calendar here. You don't have to search for updates, you'll get them as I make them in my iCal.
I wish more members of my family had Macs because this would a great tool to know who's on vacation when or when various family events are.
I like that my event alarms work on my iPod automatically. I don't need to do anything. I set it to sync once and now it just does it by itself. It's a 2-second process at the end of syncing my music changes. If I don't have my PowerBook with me on the road or something, my iPod will shout out my reminders to me on screen with a polite little "beep".
I like that I can set reminders pretty far in advance of events. It helps me get birthday cards off in the mail in good time (some relatives are very far away).
I like that it keeps the past as well as the future. Calendars aren't just for coming events. I have a calendar called "Auto Maintenance". I simply make a note of what I had done (tires rotated, fluid changes, etc) on what days and what the mileage was. Can you tell your mechanic when your last service was if needed?
It's typically Mac-intuitive. I can re-schedule events simply by dragging them to a new date. Everything associated with that event gets updated along with it.
I love that I can quickie-print a hard copy (or PDF) any any combination of my calendars (with events on them) for anybody.
I've found it's really a handy app! And it's been relatively overlooked by Apple for a while so I'm hoping for some kewl updates soon.