This is a unique service that I stumbled upon earlier today. It is called ReminderFeed and it will create a reminder for in the format of an RSS feed. I thought it was very interesting because you just put in the information about the event and it will generate the subscription links for you. Then when that day comes around it will automatically appear in your feed reader.
The only bad part is that it doesn’t offer customizability for repeating events. You can choose to have the event for a single day or for it to appear every day. Maybe options as simple as weekly, monthly, and yearly would greatly enhance the usability of the service (especially for birthdays and anniversaries).
I originally thought this was something that Google Calendar provided since you can create a feed for a specific calendar. Then I remembered that with Google Calendar the feed shows all of the events, so once you subscribe to the feed it will download everything that is currently in that calendar. That means when the day of the event comes around it will not show up again, but with ReminderFeed the event is not made available until that specific day.