The software listed here is for sharing your keyboard, mouse, and typically clipboard between PCs. You typically would move your mouse to the left or right of your monitor to access a different monitor controlled by a different PC, just as if it were part of the PC you are actually using.

This is in contrast to software like Keyclone, IS, etc which provide interaction with specific windows based on your handling of the keyboard and mouse. The software listed here can generally be used in conjunction with other multiboxing software. So, for example, I know several people who use multiple PCs and use Input Director to be able to mouse between them, and then they use ISBoxer to provide all the multiboxing goodies like broadcasting and window layouts, etc.