Free alarm clocks for Mac OS X: Pester is simple and does exactly what I want it to: let me quickly set one-off pop-up reminders. Doesn't look like it has recurring reminders, though. MP3 Alarm Clock, also very well done, plays MP3's of your choice for the alarm sound, and looks great for recurring wake-up alarms. What's your favorite?
This is BrainLog, a blog by Dan Sanderson. Older entries, from October 1999 through September 2010, are preserved for posterity, but are no longer maintained. See the front page and newer entries.
January 4, 2004