Harm acts as a four-way socket redirector that allows you to effectively make a TCP connection from the Internet to a host behind a Linux masquerade-style firewall. The server (behind the firewall) makes connections to the client (on the Internet). After a successful connection, it will bounce packets from a telnet client (Windows and Linux) to the Harm client, to the Harm server (Linux only), or to the telnet daemon behind the firewall.
console is a daemon that you can telnet to that offers a quick key entry interface (like citadel BBSes) to running scripts or other commands. The author uses it to control X-10 devices, e.g. from a TRS-80 model 100 and a Cybiko. You can define all the commands and scripts from the config file.
Sub Ether is a system that includes software to network computers together over the Internet so that applications can share resources. It is basically a grid computer over the Internet using volunteers' spare CPU and disk resources. An example application written for Sub Ether is sedistcc. It allows you to use distcc to use compilers on machines running elsewhere on the Sub Ether network.
sshh is a set of two daemons that allows you to maintain a TCP connection if all you have available is an HTTP proxy. It is similar in functionality to httptunnel, but has a few more features. Once you have it set up, sshh will allow you to make connections forward through the proxy or backwards through it, so you can open connections in either direction.