Existing users, 
Although this works really well, one should note that it is not needed to run the maintenance tasks on OSX 10.4 (Tiger). 10.4.8 has this feature built-in.
Just an FYI ;-)
Anacron
runs the periodic daily, weekly, monthly clean up tasks
Version: 3.3
Anacron NOT NEEDED on OSX 10.4.8
Feedback Type: Commentary
Contributed by: expanderz Tuesday, December 26 2006 @ 05:08 AM PST
Product Platform: MacOSX
Used Product For: Over One Year
Recommend Product: YES
Comments
Anacron still needed on OSX 10.4.8 - Ronald P. Regensburg
Some think that the daily, weekly and monthly tasks are now automatically run at startup since they are are triggered by launchd and not anymore by cron. This is not the case, anyway not on my PowerBook G4 with OSX 10.4.8.Check the modification dates of these files:
/var/log/daily.out
/var/log/monthly.out
/var/log/weekly.out
Tuesday, December 26 2006 @ 08:50 AM PST
Anacron still needed on OSX 10.4.8 - mabsey
These comments are correct.While it may appear that launchd executes the maintenance scripts "on the fly" if the computer is asleep or shutdown at the appointed time, this is a side effect of how the timer treats time the computer has spent in sleep mode. The timer used by launchd does not count sleep time. If your Mac is asleep at the scheduled time at which a given script is supposed to run, the script may run later that day, at a time shifted by the amount of time the Mac was asleep. However, if you restart your Mac before the time-shifted execution time, pending events are lost and the script will not run off-schedule: the next chance for the script to run will be at its regularly scheduled time.
If you regularly restart your Mac and the computer regularly sleeps or is shutdown at the scheduled times, it's possible that the scripts will never run, hence one should still run them manually, say on a weekly basis.
The sleep time shift is also cumulative. For example, if you don't restart your Mac for weeks or months at a time, but let it sleep when not in use, this can result in:
The daily script running once every few days or never.
The weekly script once every few weeks or never.
The monthly script once every few months or never.
The time shift in each case is the total amount of time the Mac has spent in sleep since its last restart. If you have a process that writes heavily to the logs, you can wind up devoting good hard disk space to the log files.
Saturday, March 10 2007 @ 11:30 AM PST
Anacron NOT NEEDED on OSX 10.4.8 - Ronald P. Regensburg
How and where?Does OSX 10.4.8 automatically run the three maintenance tasks at a different time when the machine is always off (completely shut down) at the times (at night after 3 AM) the tasks are normally run?
My OSX 10.4.8 certainly does not.
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Tuesday, December 26 2006 @ 07:18 AM PST