Let’s Encrypt is a free, automated, and open Certificate Authority.
The pool.ntp.org project is a big virtual cluster of timeservers providing reliable easy to use NTP service for millions of clients.
CAcert.org is a community-driven Certificate Authority that issues certificates to the public at large for free.
Matrix.org is an open network for secure, decentralized communication.
F-Droid is an installable catalogue of FOSS (Free and Open Source Software) applications for the Android platform.
Grav was with by Trilby Media.