I created this list of censorship technologies that are working today.
I believe technologies like these will eventually become an essential source of unmediated information, credit and media.
BitTorrent is probably the most popular decentralized system in the world.
Bitcoin is censorship-resistant money appears to be here to stay (decentralized).
Monero is an example of a truly private money transfer system that works. Note that bitcoin is traceable to some extent and is thus only psuedo-private.
Usenet is huge repository of media, file and documents has resisted censorship for decades. However, Usenet is somewhat centralized — individual provider will remove files by request. Also, Usenet provider ownership is increasingly monopolized.
It is a completely decentralized secure system that has been working since 2012.
The only drawback with this system is that you are limited to file sharing and communicate with people you already know (either offline or online)
Namecoin and Zeroweb
Namecoin is a decentralized DNS system — it shares domain names via a database using peer-to-peer technology. I’d consider this system still be in a beta version.
Zeronet is a decentralized web that allows you to view or create websites with “.bit” domains. It works but it is early stages of development.
Other systems that good in theory, but are very slow or difficult to use: