Why do you have to pay for third party bloatwares only to have floating events? Event Floater is my answer to this question. Event Floater does and only does what it's supposed to do: make floating events in the built-in Calendar/Date Book. You don't need any additional databases.

After installation, you can find "Event Floater" from within Prefs. Just set up the trigger time and the format prefix for floating events. Simply remove the prefix to make events plain appointments. It's like checking the completion box in Tasks.

In OS 4 or below, Event Floater is triggered at the specified time. If 00:00 is given, it will be triggered 60 seconds later (at 00:01) to make sure of date change. After then, it will run every 24 hours. If you're in Calendar, Event Floater will wait for you to exit to prevent potential conflicts.

In OS 5, setting the trigger time to 00:00 lets you use the notification manager for database update. That is, whenever you launch/quit Calendar/Date Book, Event Floater "immediately" moves past floating events to today. If time other than 00:00 is given, it behaves exactly the same as in OS 4. Setting to 00:01 is basically the same as setting to 00:00 in OS 4 because of the 60 second delay.

Why do I have to put the two ways for trigger? Each method has the following disadvantages over the other:

OS 4
Whenever Event Floater is periodically launched in sleep mode, LCD will wake up and go off after some time. The job is not completely hidden from the user.

OS 5
Notification events that Event Floater uses are supported only in OS 5.