From Alan Howie:
Clicky Gone allows you to hide your selected windows from view; this includes the taskbar button associated with the application. This utility particularly helps with protecting your privacy by hiding things like your browser with banking details up and someone walks in on you. There is no need to close your applications if they are taking up to much space on your desktop or taskbar. Each window you hide can optionally be placed as a small icon in the system tray for easy recovery.
Features include run hidden windows application's in the background, i.e Low priority, toggle all windows to hide and show, Boss Key support, hide the active window and mute the sound, and prevent click hiding on full screen applications, i.e. Games.