This is the holy grail of rock solid email templates from Mailchimp, Zurb's Ink and Antwort. For previews and easy html access, see http://cjmosure.github.io/email-blueprints/. Cheers.
Brought to you by MailChimp, these email blueprints are licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License. See MailChimp's HTML Email Reference for their best practice guides.
/modular-template-patterns contains a single template built out of modular blocks of common design patterns.
/responsive-templates contains a collection of responsive / mobile-friendly email templates with various layouts.
/templates contains a collection of fixed-width email templates with various layouts.
When inlining the CSS in the responsive templates, be sure not to include the styles within the media query; they should remain in the head element of the email. The MailChimp app and external CSS inliner both inline the CSS correctly, but many services may not.