I don't know if this is new to people, but I just discovered that the *NIX at command finally works in OS X Tiger. I know that I've tried getting it to work since 10.0, with no luck (but maybe I missed it in 10.3).
For those of you unfamiliar with it, at allows you to run command line tasks at a specified date and time. I first used it when I was teaching, and wanted to post exam answers at a specified time (after the exam was given). I could put the answer-key html file on the website the day before I wanted it viewable, but set the chmod to disallow access. Then I would issue the command:
I've found this command to be very useful in scheduling one-off kinds of events, like running a job late at night or even setting reminders.
$ at 3:30pm tomorrow [hit return] chmod +r exam1key.html [hit return] [hit Control-D]
I am pretty sure you have to reboot the machine for it to kick in. I highly recommend checking out the man page, since you'll see how straightforward this tool is. Ff you aren't familiar with these other useful command line tools, also check out nice (and renice) and nohup.
$ sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.atrun.plist
Mac OS X Hints