Focus the user on some sidebar content, and blurring the useless content.
This way, the user can focus on your sidebar, and the blurred effect create a smooth & not-intrusive way to do it.
Of course, we want it to work everywhere, or almost everywhere ;)
The effect can be applied to Firefox, Webkit browsers (Chrome, Safari, etc) and IE
If you liked the idea, and want to contribute, I will open a github repo dedicated to it soon, but you can fork it, modify it and/or use it as you want.