Recently, Apple enabled CalDAV subscriptions on the iPhone (which also play well with Google Calendar); that made me dust off my copy of iCal and take a second look. If you're not using iCal at all, you may want to take a moment to learn about what you can do with it.
The idea of calendar subscriptions is simple: store a calendar event database somewhere online, and then provide a link in a common format for calendar programs such as iCal to access. The calendar program then imports the calendar data and puts it in your calendar, updating itself at a frequency of your choosing.
Online databases of public calendar links abound, and you can add calendars from your local little league schedule to stargazing guides to the galaxy in your area. The format that Apple uses is the "ics" format, and you'll see calendars with that extension all over the web. Apple itself provides a place to browse calendars, which you can also access by pulling down the "Calendar" menu within iCal and choosing "Find Shared Calendars...." You'll find greater content depth at places like iCalShare and iCalWorld. (NB: Unfortunately, both of these sites seems to have trailed off with database updates, but the calendars within them can still be current and they still provide a wealth of calendars to browse.)
If you click on "subscribe," you'll automatically enter iCal and it'll open the subscription dialog box. Click "OK" and then choose how often you want the calendar to update (iCal's default is not to update at all, so be sure to change that if your calendar is a rolling one.) If you come across an .ics link online, you can enter that calendar address directly in iCal by choosing "Subscribe..." from the "Calendar" pull-down menu.
Now that you know how to subscribe to calendars, the fun begins. Did you know, for example, that you can "subscribe" to your local weather through a calendar? Go to the Weather Underground. Enter your zip code. Look in the upper right-hand corner for the "iCal" button. That takes wunderground's data feed and automatically translates it into a format iCal can understand. If you merely click on it, you'll download the data file in ics format which you can import into iCal, but that's only this week's information. Here's the magic: if you "subscribe" to the .ics feed, you'll get automatically updating weather forecasts, right in iCal! So right-click or control-click on the iCal link, and choose "copy link location." Then go to iCal and choose "Subscribe..." Put your link there. Bingo.
Once you've got the hang of subscriptions, it's a hop step and a jump to the power of CalDAV, which gives you even greater flexibility and true, two-way event management from all your devices.