For WordPress the integration with Akismet is an ideal solution for removing spam comments from your website. Until recently this tight integration was not available for Drupal. While Akismet was available for Drupal it lacked some of the abilities that WordPress included.
This was until Mollom became available for Drupal, designed by Dries Buytaert, the founder of Drupal. Mollom works in a similar way to Akismet however has tight integration with Drupal. A free version is available for smaller sites and a professional version for busier sites costing 30 Euros/month.
For more about Mollom visit:
For more about Drupal visit:
I have tested Mollom on a number of client sites and will be implementing it soon on our parent website, www.imafish.co.uk .