Google Open Source - All of Googles open source projects under a single umbrella
Templates by Email Monster - Hundreds of free, responsive email templates. Pick and edit.
LaunchKit - Open Source - A popular suite of developer tools, now 100% open source.
SaaS Email Templates - Responsive HTML email templates for SaaS startups
Open Source @IFTTT - A collection of IFTTT OSS projects.
Email Template Generator - Email templates for your important relationships