Between sessions: cut/paste, multiple on one screen, dual monitors
 

Does anyone recommend any software for linux that allows you to do useful things such as:

-cut and copy between window sessions (not just console ones, actual window manager sessions).. i.e. if I hit CTRL-ALT-F8 I want to pass stuff between windowing sessions via ctrl-c, ctrl-v, OR
-use multiple window manager sessions on one screen, pass stuff that way
-use multiple window manager sessions on two video cards/monitors on the same computer, each dedicating a monitor to that session/videocard, and pass stuff that way.