Windows: If you're tired of a taskbar cluttered with applications that you need to have open but can't be properly hidden or minimised, HideIt allows you to minimize any application to your Windows system tray by right-clicking its minimise button.
HideIt is similar to some other apps we've discussed in the past, like Trayconizer and RBTray, but is actively developed and unlike the others, was built for Windows 7. If you right-click the minimise button on any open window, you'll see the option to minimise the window to the system tray instead of the taskbar.
Similarly, if you right-click the HideIt icon in the task bar, you can select which windows or applications to restore, or restore everything at once. Best of all, it's completely free.
HideIt – Hide All Your Windows [deviantART]