Is there any way to block windows into a specific area on a screen, so when they maximise they don't stretch over top of the whole desktop and hide my desktop widgets?
Dear Hidden Widgets,
You can use the previously mentioned DesktopCoral application, which reserves a section of the screen so that maximised windows can't use that area—as if there was a sidebar there.
Using the application is a little strange the first time, so we'll take you through a quick run-down of how to use it. After installing and launching the application, you will need to drag the small dialogue to one of the edges of the screen, where it will dock like a sidebar.
Right-click on the docked Desktop Coral window, and open up the Options window. Make sure the Docking Position is set to the correct location, check the "Transparent Mode" box, and you should be ready to go.
In my experience, you sometimes need to restart DesktopCoral after changing the settings, but your mileage may vary. The only real annoyance with this technique is that you can only block off a single side of the screen—but still very useful for customising your own killer desktop.
Love and Geekery,