Stackshare - StackShare is a comprehensive website that gives its users the chance to organize and share their technology stack with the rest of the community.
Startup Toolkit - Interactive how-to guides to launch your startup
Siftery - Share products your company uses and get personalized recommendations
JumpStart Toolkit - A pack of tools and goodies to jumpstart your startup
Techmap.io - Techmap is a workplace search engine to find companies using technologies (e.g., Rails, PHP, Java, etc.) that are used internally. Finally, a "Google for Workplaces" that helps people find a place to work with technologies they love!
Techstars Entrepreneur's Toolkit - Online resource to help you learn about entrepreneurship