One of my favorite desk accessories on the old Mac was the Alarm Clock. Mac OS X doesn't have one. Neither does Windows. I miss it.
I don't know why it disappeared. I guess they figure the appointment-setting features of iCal, Outlook, or Entourage eliminate the need for a simple alarm clock. But they don't: I often want my computer to remind me when a TV show is coming on, or to check the oven in ten minutes, or for other impromptu events, and I don't want to go through the whole process of creating an appointment (specifying date, time, length, location, who's attending, etc.).
I found a few alarm-clock utilities for OS X, but none of them do exactly what I want, and the more useful ones are not free. So I may need to write my own alarm clock application. This will be my chance to learn to write a Cocoa app.
In the meantime, I'm just going to use the UNIX 'at' command from the Terminal to trigger the speech synthesizer. I can use it like this:
localhost:~ kdj$ at 13:50say -v Vicki 'Kris, it is time to go back to work!'^D
and then a soothing female voice will gently wake me from my afternoon nap.
If you decide to use 'at' yourself, be sure to read the man page for at. It is necessary to enable the 'atrun' command in /etc/crontab before it will work.