Pariahware has released Days Away 1.0, a Mac OS X application that periodically reminds you of upcoming events by fading into focus, pausing for you to read the events, then fading back out.
To use the US$10 software, you add the date that needs to be remembered by clicking on a calendar and adding the name of the event. Periodically, Days Away will fade into view so you can see how far away the date is. You can use Days Away to remind yourself of due dates, birthdays, anniversaries and other occasions.
Days Away is made with the REALbasic development environment from Real Software.