DesktopCoral is a freeware that blocks a part of your desktop so that no application covers that area. It is like a fixed docking bar on your desktop, that you can have on any side of desktop. You can also control height of this docking bar, and that part of your desktop will not be occupied by any application.
DesktopCoral is especially useful if you want some programs or some information to be always visible, even when other applications have been maximized. In my case, I would like to use such a space to put controls of some media player like Winamp, or Youtube desktop player. Other uses could be to monitor some processes, or to just see system information with tools like Samurize.
DesktopCoral is completely resizeable. Apart from that, you can also control opacity of the area that you reserve by using DesktopCoral. DesktopCoral also lets you choose some image from your PC that you can use as a background for this area.
If you have a specific need for such a tool, DesktopCoral is definitely a good choice. It is easy to use, and completely free. Download DesktopCoral here.