Scan of every page of my sketchbook before I threw it in the sea.
An interesting article about throwing away art at the Off Modern website, concerning Michael Landy's Art Bin. Artists were invited to have their work considered by Landy himself and then if deemed enough of a failure the indivudual could throw away their work.
In 2002 Landy destroyed all 7226 of his possessions, as detailed by this article on the Guardian. He said he felt 'free'.