UPDATE: the MailChimp “Classic” embed form now supports inline/ajax submission without a redirect. So, you probably don't need this. Maybe only if you really want to customize.

An example mailchimp signup form, without redirects.

To use the example:

• Download ajax-subscribe.html
• Replace the form action url with your own from the MailChimp supplied embed code
• Within the action url, replace "subscribe/post" with "subscribe/post-json"
• Be sure the action url starts with http://. If it doesn't, the form will hang when testing the html as a local file in your browser.
• Open the html file in a browser on your local machine