Also, if you've done this:

    you@somehost:~$ ssh otherhost
    you@otherhost:~$ some_command

If you hit ^Z right now, it will tell the shell on otherhost to stop some_command and give you the shell prompt on otherhost back.

If instead you wanted to stop the ssh process and get the shell prompt on somehost, hit Tilde ^Z (you don't have to hit a new Return, but ssh only notices these escape sequences after a Return).

Also if you use ControlMaster and have a few xterms open all with sshs to otherhost, and then you exit the first ssh you happened to have open, it will seem to hang and not give you your prompt back. What's happening is that that ssh process is the "control master" and it's still open because you've got other sshs to the same host open. Hit Tilde & to background the ssh process and get your terminal back.

Yes, you could also hit Tilde ^Z and then 'bg' the ssh process.