HTML Email Templates

Resources with canned or easy to customize email newsletter templates that (should) work with most or all email client software. Your mileage will vary. And don’t forget to test your emails before sending.

Campaign Monitor

http://www.campaignmonitor.com/templates/all/
http://www.campaignmonitor.com/resources/

MailChimp

http://kb.mailchimp.com/article/what-templates-do-you-have-besides-the-free-ones-i-can-download/
http://templates.mailchimp.com/

Themeforest

http://www.themeforest.net/category/email-templates