I usually use long running X sessions with several virtual desktops and many many xterms.
I also use job control in the shell (zsh).
Sometimes I wish I could identify an xterm a shell or process is running in (or even suspended in) with a simple command.
For example, you edit a file with vim and vim warns you that it is already opened with another vim instance which is still running. But now you have forgotten in which xterm this vim with process-id XYZ was started and suspended. Killing it does not work, because it is suspended. Resuming it via a signal and then killing could work, but it may screw up an in-foreground running process and perhaps you don't want to kill the vim instance because it has several windows set up ...
Currently I am using awesomewm, but I am also interested in solutions for other wms.