DM2 Portable is a handy desktop tool that allows you to manipulate the windows of running applications in a variety of useful ways.
Do you sometimes run so many programs that it's hard to pick them out on the taskbar, for instance? Then DM2 can help. Instead of minimising an application as usual, right-click its minimise button and choose the new DM2 option, "Minimise to tray". The program button will disappear from the taskbar, freeing up valuable space, and be listed in your system tray, instead (just click it to restore the program window).
Or maybe your system tray is cluttered, too? Right-click the program's minimise button and choose "to floating icon". The program icon will appear top-right on the desktop, and you can right-click it to restore the window or apply other actions.
If a window is particularly important and you need to keep an eye on it - a program that's displaying a graph of your CPU temperature, say - then right-click the minimise button, select "Always on top", and it'll always remain visible above your other application windows. (Choose the option again to toggle this setting off.)
Or, if you'd like to see what's happening beneath a window, use the right-click option to reduce its opacity and it'll become transparent, so you can see other windows that may be displayed beneath it.