I have a multi-monitor setup where only one of my screens has a panel with a task manager. It would be nice if the task manager provided an option to group tasks according to what screen they are on. It would also be nice if the task manager provided an option to somehow mark tasks (for example, with a different background colour) according to what screen they are on. This way the user can see at a glance what task a screen is on, even if the user has decided to group the tasks according to some other criterion.
Not a bad idea.