Shell could have the ability to "zoom out" to a view of all the currently loaded web pages presented as tiles which can be "zommed in" to. Something along the lines of Expose in OS X or Panorama in Firefox.

Tabs could be grouped into workspaces and those workspaces could presented as a row of tiles.

[[Image(workspace_as_row.png)]]

Alternatively the workspaces themselves could be the tiles

[[Image(workspace_as_tile.png)]]