Additional Workspaces
Solution 1:
9 workspaces for you
gsettings set org.compiz.core:/org/compiz/profiles/unity/plugins/core/ vsize 3
gsettings set org.compiz.core:/org/compiz/profiles/unity/plugins/core/ hsize 3
:)
Solution 2:
Unity Tweak Tool will let you go up to 6 workspaces easily.
Just go to Workspace Settings
under window Manager
here you can set how many horizontal and vertical workspaces you want in the grid.
Solution 3:
I will assume by WORKSPACES you mean "virtual desktops"
You can easily set these in CompizConfig
sudo apt-get install compizconfig-settings-manager
Then
ccsm
Navigate to "General Options"
Select Desktop Size. Boom!