Oh, I guess I was trying to extrude from standard mode instead of polygon mode. Thanks for the help, Mayaniac.
Originally posted by Mayaniac
Right hand mouse click on your object, and select "Polygon" this will put you in polygon mode, and you can then select the face and extrude it.
Then simply right hand mouse click on the object and select "Standard" this will allow you edit the Sub-Ds again.