Tor is a privacy/security solution I have previously written about. Tor is not perfect, and, periodically, there are reports of successful attacks against the system by various nation-states and third-party groups.
TrueCrypt was a popular, source-available program that was used for on-the-fly encryption. Its developers abruptly ceased work on the project, but an ongoing, third-party audit has found the program to be sound.
You can donate to the project via the project's home page.
I am becoming increasingly interested in versions of Android that offer additional privacy/security controls and that are less dependent on Google and their services. It is still early days, but Cyanogenmod has made significant inroads and is a popular, Android-based operating system.
There are several ways to participate in the Cyanogenmod community, including code review, working on the Cyanogenmod Wiki, and donations.
The Internet Archive
The Internet Archive is a non-profit library that offers free, public access to a huge collection of digitized materials (e.g., websites, applications, games, music, movies, public-domain books). Their aim is to provide permanent access to extant historical collections in digital form for researchers, historians, and scholars.
Also, they offer the Wayback Machine, an awesome, digital archive of the World Wide Web, which allows users to see archived versions of pages across time in a three dimensional index.
Libraries are an integral part of fully functioning societies, and, in the digital realm, you can not get any better than the Internet Archive.
The Mozilla Foundation
The Mozilla Foundation is a non-profit organization that supports openness, innovation, and participation on the Internet. Personally, I do not want to live in a world that is completely dominated by Apple and Google.
The Mozilla Foundation and the products they support have helped push the Web forward and ensure that there is always a free and open alternative to the closed systems that the ascendant, tech giants of the day have to offer.
These organizations are just a sampling of the larger community that is in the vanguard for addressing the serious obstacles that the digital world is facing. They fight the good fight and need continuous support.
If you have the resources or the time, please consider supporting them today.