Cron Job in Magento

A few features in Magento require a script to be run periodically.  These features include, but are not limited to:

1. Catalog Price rules

2. Sending Newsletters

3. Generating Google Maps

4. Customer Alerts/Notifications (product price change, product back to stock)

5. Automatic updating of currency rates

Setup Cron Job in Magento:

http://www.magentocommerce.com/wiki/1_-_installation_and_configuration/how_to_setup_a_cron_job#magento_and_crontab 

Magento Cron Scheduler
http://www.fabrizio-branca.de/magento-cron-scheduler.html