I have been checking out this YouTube user lately. She does some impressive heavy metal covers on the piano. She even does the really difficult guitar parts that are extremely hard to translate over to the piano. I believe that she is a classically trained conservatory musician who found out about heavy metal later in life, after beginning to study classical piano.

Here is her YouTube profile: http://www.youtube.com/user/vkgoeswild
Here is her website: http://www.vkgoeswild.com/

You can download mp3s of her covers (and I believe a few originals as well) for free. You can also download sheet music for her covers.

Check her out. She is amazing!