If you are spoiled with a multiple monitor setup, and using Ubuntu, like me, you might be wondering whether it is possible to not have all your windows from your different monitors in one taskbar. The solution is easy: create a new panel by right clicking on an existing panel and choosing New Panel. Drag this panel to (one of) your additional monitor(s) — use the alt key to start dragging. Finally right click your new panel and choose Add to Panel..., and select the Window List item. That’s it; the newly added window list will only have buttons for those windows on that monitor where its parent panel is on.
Multi-monitor window lists are a feature of Gnome, so the steps mentioned earlier are not limited to Ubuntu.