Anonet is a decentralized IP based darknet. It's implemented as a bunch of (mostly peer to peer VPN tunnels over the internet, and (usually Linux based) BGP speaking IP (mostly IPv4) routers.
Anonet has claimed the IPv4 subnetwork 220.127.116.11/8 to provide every participant with sufficient IPv4 addresses to address the entire network with 'publicly' routable IP addresses. There's usually no need for NAT on Anonet, and people tend to use it to connect to their own computers from locations that would otherwise not allow them to do so (think breaking through firewalls).
Anonet's ultimate goal is to replace the internet as we know it, to provide everybody with a free (freedom of speech) and censorship resistant network, without one ever growing centralized government. Whether this will ever happen is unsure, but resistance against control and censorship by our governments is definitely growing. If you're not in for the freedom, not all hope is lost yet. Anonet is a great place to learn about- and experiment with all kinds of computer networking concepts and technologies. As a participant, you will learn a lot about Virtual Private Networks, BGP, IP routing, Linux, programming and computer networking in general. You can freely deploy your own experimental services, protocols and applications.