SmartSystemMenu - SmartSystemMenu extends system menu of all windows in the system
Glass2k - Small little program that allows Windows 2000/XP users to make any window transparent.
RBTray - Allows almost any program to be minimized to the system tray by right clicking its minimize button.
GhostWin - GhostWin - Free Download -- Transparent Windows Utility supports Windows 2000, 2003, XP, Vista and 7
Clicky Gone - Clicky Gone allows you to hide your selected windows from view, this includes the taskbar button...
Feewhee - Feel the Wheel (Feewhee) is a tool that Microsoft apparently overlooked while making Windows.