The community I am really passionate about is the Free Software Foundation(FSF).
We go about our days without realizing that most software we use is proprietary. Proprietary software is pre-installed and pre-configured on your devices. This means that there is no way to inspect the code and determine whether there it is authentic or not and they in no hurry to change that. You can bet that most proprietary software contains spyware. We have seen this through numerous scandals in news articles and revelations from Wikileaks. The deception is vast. It starts with apps like Facebook that openly spies on it's users and goes all the way down to the underlying hardware like Intel processors that include backdoors into your system.
This unjust amount of control coporate developers have over their users is something companies are reluctant to give up - it is a very profitable venture.
The Free Software Foundation is dedicated to creating truly free and open-source alternative software, like the now infamous GNU and Linux systems. Software that anyone can download install and run on their computer. Software that anyone can contribute to and modify as he wishes. Software that is truly transparent, one where anyone can examine the source code.
This amazing community of developers that voluntarily fight for liberating the digital world is one I am most passionate about. In this digital world which is becoming more and more interconnected, user privacy and internet freedom is becoming more and more important. Their work deserves much more public visibility and appreciation.