Joomtraders has created allChimpRegister to allow for easy subscription and unsubscription of guests, without having to externally link to the forms provided by MailChimp.
First released in November 2009, this extension makes use of AJAX to ensure that users do not navigate away from the website page they are viewing when submitting their details.
The extension is a single module file, allowing for easy placement within a Joomla! website and comes with pre-created classes, so that it can be styled using CSS to suit individual tastes and website designs.
The latest version, version 2.0.1, is compliant with Joomla! 1.6, 1.7 and 2.5. The latest version contains a fix for allowing dashes/hyphens in email addresses.