About couple of months ago we did demo for one client.
we created simple skin​, no code changes, just css and templates.
and it is still online http://skin-demo.zojax.com/




if skin-demo.zojax.com doesn't work, try direct link http://67.18.229.59:50680/parea/

Here another example. i ported iNove Wordpress Theme to z3ext. it is not released as egg,
but available from sourceforge.  it is not completed and probably wont be released as egg.