Have you tried using a pair of vice-grips? Grab the edge of the plug... back it out.
I once stripped my plug... but managed to get it out. Promptly went to Auto Zone... dropped a few bucks on a steel plug... haven't had a problem since.
Oh. Never have I torqued my plugs when doing an oil change... on any car ever I've owned. 100% has worked out for me... and never a weep or leak.
