WPML integration for the Mailchimp for WordPress plugin.
Shows activity for your Mailchimp lists, right in your WordPress dashboard.
Add a Captcha field to your MailChimp for WordPress sign-up forms.
Synchronize your WordPress Users with a Mailchimp list.
Flexible call to action boxes, a better alternative to pop-ups.
WP Newsletter Subscription is an excellent plugin to boost up your mailchimp subscribers list.