Siftery - Share products your company uses and get personalized recommendations
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.
WhatRuns - Extension that helps you identify technologies used on any website at the click of a button.
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!
Software Product Management Stack - Resources & tools to help you manage your software product
xZeitgeist - The most popular tweets categorized and ranked, every day