SmartSystemMenu - SmartSystemMenu extends system menu of all windows in the system
Clicky Gone - Clicky Gone allows you to hide your selected windows from view, this includes the taskbar button...
RBTray - Allows almost any program to be minimized to the system tray by right clicking its minimize button.
Hide my Windows - HMW is a free program to hide away the Windows on your desktop.
Glass2k - Small little program that allows Windows 2000/XP users to make any window transparent.
Minime - Minime is a tool that allows you to minimize applications to the system tray using a simple hotkey.