Add a custom column to Wordpress Post management page after title column: Full article at: http://imelgrat.me/wordpress/customize-wordpress-post-management-page/

add-column-middle.php

add_filter('manage_posts_columns', 'add_column_middle'); // Register filter

function add_column_middle($defaults)
{
	$new_columns = array(); // Create empty array to store new column order

	foreach ($defaults as $key => $value)
	{
		$new_columns[$key] = $value; // Add columns to new array
		if ($key == 'title')
		{ 
		    // when we find the title column
			$new_columns['wordcount'] = 'Word count'; // Add the word-count column after title column
		}                
	}

	return $new_columns;
}