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!
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.
xZeitgeist - The most popular tweets categorized and ranked, every day
Siftery - Share products your company uses and get personalized recommendations
Top Lists - A leaderboard for Twitter lists
listshare - Create beautiful, interactive lists to share with the world.