Adding a top tier tab to a custom object extension

[panic4az]

Is it possible to add a top tier tab to a customer object extension?  There are several tabs defined; Getting Started, Summary, Monitor, etc., but can a different named tab be added?  If so, can you point me to some sample code?

[laurentsd]

Top level tabs are not extensible.  This is done on purpose in order to keep the consistency of UI between all the views.