Dexpot - If you don't have Dexpot yet, the new update makes it a must-have tool for Windows, adding a ton of features to your desktop that you never knew you wanted.
Glass2k - Small little program that allows Windows 2000/XP users to make any window transparent.
VirtuaWin - VirtuaWin is a virtual desktop manager for the Windows operating system (Win9x/ME/NT/Win2K/XP/Win2003/Vista/Win7/Win10). A virtual desktop manager lets you organize applications over several virtual desktops (also called 'workspaces').
RBTray - Allows almost any program to be minimized to the system tray by right clicking its minimize button.
Sysinternals Desktops - Desktops allows you to organize your applications on up to four virtual desktops.
DeskPins - DeskPins can be used to make any application topmost, that is, to keep it above all other windows.