Every so often a program you are writing needs to accept a password (or some other private information) on the console.  It would be really nice to not echo the keyboard input.  This is actually really simple, but it is difficult to find documentation on.  There is a command to "change and print terminal line settings" (stty).  Keyboard echo is one of these settings.  In your program, or directly in a shell, simply run the following command:

stty -echo

This will turn off keyboard echo. To turn it back on:

stty echo