I have been using this service for quite a while now. It's called
iCal Exchange. What it allows you to do, is sync all of your iCal events online w/o having a MobileMe (formerly .Mac) account.
Why is this handy? Well, if you have iCal on a computer at home and a computer at work, you can use it to access you calendars on both. Not only that, but once you get it synced online, you can set up your Google Calendar to sync with those online iCal events. This brings all of your calendars together, making it much easier to keep track of everything going on in your busy lives!