Hunter TechLookup - Create lists of websites by technology for free
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!
xZeitgeist - The most popular tweets categorized and ranked, every day
Listshare Group Lists - Easily share group lists with your family and friends
Top Lists - A leaderboard for Twitter lists
Checkly - Fresh API monitoring and Site Transaction Monitoring. From one great dashboard.