Free Countdown Timer is an easy-to-use reminder program, that allows you to set up multiple timers for important events, then alerts you as they approach so you need never forget anything again.
The program comes with plenty of configuration options. So you can set a timer to go off at a specific date and time, like "10pm on January 15th 2011", or after a particular period of time ("two hours and thirty minutes from now"). When the timer reaches zero you can stop or restart it (the latter option would allow you to have an alarm every hour, say). You can customise the alarm sound, and decide what happens when the alarm goes off (the program can turn on your monitor, and wake up your PC from sleep mode).
There's also a useful option to set your system's audio level for the alarm. So if you've accidentally turned it right down, say, Free Countdown Timer can ramp the volume back up again, ensuring you won't miss its alerts. (Or if the volume's been turned up to the maximum, then Free Countdown Timer is able to restore it to something more acceptable, so the alert won't blare out unexpectedly and annoy everyone else around you.)
And of course you can add as many timers as you like: holidays, birthdays, anniversaries and more. Free Countdown Timer will track them all and warn you when they're due.