T-Minus Anniversary Countdown
Whether it's your first or your fifty-first anniversary, now you can count down the time to this special date. You can play our "champagne toast" or insert your wedding song as background music! Tell your spouse you'd do it all over again by tracking your anniversary. ... A software program for your PC that's fun and easy to use.
http://www.thecountdownclock.com/Downloads/T-MinusAnniversary.exe - 4Mb - Download - Screenshot

Countdown
Countdown! takes up to 100 dates in the past or future and calculates the number of years, months, days, hours, minutes, and seconds. Also the total number of hours, minutes, seconds and weekends are displayed. The screen is refreshed each second so you can get an interesting look at elapsed time. ... Used by members of the US Military stationed around the world to tell when they are going home, anniversaries, birthdays, etc! ... You can tell exactly how many weekends remain since the year 2000, how many seconds you have been alive, or how many days until your anniversary.
http://www.elt2.com/software/cntdwnsetup.exe - 778Kb - Download - Screenshot

ActiveEarth
ActiveEarth is a world time clock with a gorgeous day/night merge of NASA's Visible Earth satellite images in flat maps or a globe, with a row of user-definable clocks along the bottom. These clocks are beautiful, scalable, ticking, analog clocks that come in several styles with many custom... ActiveEarth allows you to countdown to future astronomical events and to specify your own custom events. ... The program can play an alarm sound to help you remember a birthday or anniversary. ... You can track important future events with countdown clocks!
http://www.activeearth.com/Download/AE2_2097.exe - 3Mb - Download - Screenshot