If you work a lot using the cron jobs, it makes sense to check the syntax that you are using. This is more so if you have something that runs only once a day or month.

I got across this link http://www.hxpi.com/cron_sandbox.php which gives you a list of date/time when your script would run based on the syntax provided.

Amitabh

Update: It seems that the site registration expired and a link farm has come up in its place.