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.

LinkedIn Salary - Discover your earning potential

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!

The Cheddar Counter - How much do you actually earn?

WhatRuns - Extension that helps you identify technologies used on any website at the click of a button.

Founder Salary Calculator - Unsure how much to pay yourself? Check out this calculator.