In Mac OSX, you can configure the screen corners to exhibit certain behaviors, such as show desktop, display list of windows, start screensaver etc. In Linux, you can do all these as well with Brightside.
Brightside is an application that adds reactivity to the corners and edges of your GNOME desktop. It is small in size, but brings great dynamism to your desktop.
In your terminal, type:
sudo apt-get install brightside
Alternatively, go to Synaptic Package Manager, search for brightside and marked it for installation. Then click Apply.
Once installed, go to System -> Preferences -> Screens Action.
By default, none of the corners are checked. Choose the corner that you want to act action to and put a tick on the box beside it. On the right, you can choose any of the preset actions, or simply define your own. Some of the preset actions include Mute volume, Prevent screensaver from starting, Start screensaver, go into standby mode, go into suspend mode and show desktop.
Just below the configurable actions is a drag bar where you can set the time to activate the action.
If you are using more than one workspace, there is also an option for you to switch to adjacent workspace when mouse is moved to edge of screen.
Once you have finished your configuration, click Close. You can now thrust your mouse pointer to the corners and see the effect in action.
To enable this application everytime you log in, go to System -> Preferences -> Sessions. Click Add.
In the window that appears, enter Screen Action in the name field and brightside in the command field. Click OK.