ssh

If you're out and about using untrusted networks (your favorite WiFi hotspots, someone's unsecured WiFi as you randomly drive around looking for a connection, etc) you might not want to be doing your internet business over that connection in case someone is sniffing the network. By using a SSH server on a network that you do trust you can create a secure SSH tunnelled SOCKS proxy, set your web browser to use it and you're at least doing your business over an encrypted connection.

SSH (secure shell) allows you secure shell access to a server from a client across any network (local or Internet) with the comfort in knowing that your information is secure (even your password used to log in). Everything that travels across a SSH connection is encrypted. Typically you'd use SSH for executing terminal commands at the server (restarting HTTP servers or managing your MySQL server for example) but it also supports port forwarding, tunneling and even file transfers.