Ubuntu – Ring Switcher in Unity

The closest you can get is to use the Unity launcher. If you are on a workspace that has your browser running, clicking on the browser icon in the Unity launcher will display all the open application windows for that browser.

If you are not on the workspace with your browser windows, clicking on the browser icon in the Unity launcher will take you to the workspace with the browser window you last interacted with.

A side note. If you have all your browser windows on one workspace, you can cycle through your browser windows by clickig the middle mouse button on the top panel in the gap between the global menu and the indicators.

A nice guide to mouse and keyboard actions is at OMG Ubuntu http://www.omgubuntu.co.uk/2011/04/become-a-natty-power-user-in-no-time-using-this-unit-keyboard-shortcuts-wallpaper/

There is a workaround:

First of all, install the following package:

sudo apt-get install gnome-panel

1. Then, launch a terminal and run the command gnome-panel.
2. Look for the old style workspace icons. By default, it's located at lower right corner.
3. Right click on it and choose Preferences.
4. Set the number of rows, in your case, to 2.
5. Your should get the new workspace changes. Close the window.