In an earlier post I had written about how to Easily convert your laptop to a dual monitor system using your spare monitor.
If you already have a working dual monitor system you would notice that while you can port any window to the secondary monitor, the windows taskbar only appears in the primary monitor. Windows will not extend the TaskBar to the other monitors and all windows will be shown on the single windows taskbar on a primary monitor.
Multimonitor Taskbar is a free tool that addresses this problem. What it essentially does is, it adds a second taskbar to the extended desktop on Monitor 2.
This second taskbar shows only applications that are open in that monitor. Similarly, the taskbar in your primary monitor will now show only applications open in the primary monitor. Multimonitor Taskbar supports upto two secondary monitors. So if you have a third monitor, a windows taskbar will be displayed in the third monitor.
Multimonitor Taskbar also adds a convenient Move to Monitor button to windows applications.