WpRecipes.com - Daily recipes to cook with WordPress

Just paste this piece of code in your functions.php file:

if (!wp_next_scheduled('my_task_hook')) {
	wp_schedule_event( time(), 'hourly', 'my_task_hook' );
}

add_action( 'my_task_hook', 'my_task_function' ); 

function my_task_function() {
	wp_mail('you@yoursite.com', 'Automatic email', 'Hello, this is an automatically scheduled email from WordPress.');
}

On line 1, we created an event, after verifying that an event of the same name wasn't already registered. All we have to do then is to create a function to do what you want (In this example, the function is called my_task_function() and it simply send a dummy email) and hook this function to any WordPress event.