Where is my crontab file? I want to edit my crontab file to schedule a script. Where do I find it?
In Mac OS X Lion the user crontabs are stored in /var/at/tabs. In the past they were located in /var/cron/tabs.

You should use crontab -e to interact with these in general, but knowing the location is useful for when you want to restore them from a backup of your disk, or something similar.