By default, it seems that the Alt-Tab popup for switching between applications shows on whichever monitor contains the active window. Is there anyway to duplicate the alt-tab popup on both monitors all at once?
If not, is there a way to force it to always appear on one distinct monitor so it doesn't always seem random?
This is currently not possible in Unity without modifying the source code to implement this feature, sorry.
As of Ubuntu 13.10 (and possibly earlier) this has been fixed. The Alt + Tab program switcher now displays on the monitor where the mouse cursor is located, regardless of where the active window is. Thus, it is more intuitive.