Automatic HTML style inlining
When designing HTML emails, having to use inline styles (style="xxxx") instead of CSS classes is a right old pain.
There are tools and libraries that can take a HTML document, and automatically 'inline' the CSS styles. E.g. http://beaker.mailchimp.com/inline-css
It would be AWESOME if there was an option to apply this transformation to a HTML email before it gets sent....
Don Hawkins commented
Why make your customers go to MailChimp to inline their CSS? Get it on the API already, easy stuff.
Mailchimp not only have online tool, but actualy API option for css inlining.