Hunter TechLookup - Create lists of websites by technology for free
Timeline - Timeline is a cross-platform application for displaying and navigating events on a timeline.
Setalist - The easiest way to make awesome lists for the internet
MyTweetAlerts.com - Like Google Alerts for Twitter
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!
SOCIALHOSE.IO - Discover an enterprise social listening platform that enables brands & agencies to monitor the web & listen to their audience, built to scale. Start for free!