Do You Even List? - Auto updating Twitter list of people you interact with most

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.

Listr - Listr lets you explore some of the best lists on Twitter, curated across your favorite categories.

Setalist - The easiest way to make awesome lists for the internet

Vicariously.io - Create Twitter lists based on the follows of other users

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!