[ak217]

Best trick I learned in the past few years is SSH control sequences.

Disconnected from your host but not timed out yet? Press Enter, ~, . and the client will quit.

[themckman]

Ohh my, the day I learned this was one of the happiest in all my life. You can also configure this in your .ssh/config with EscapeChar, if you find yourself SSHing into other machines from a machine you're already SSHed into.

[eieio]

You can also use send a double tilde ( Enter, ~, ~) to pass a tilde to your inner ssh session. So killing a session within a session is Enter, ~, ~, .