Going to implement this sometime soon: How To Block The Diggbar.
UPDATE: Implemented with a simple mix of PHP and JS. URL detection is server-side á la Gruber, redirection is via JS. Why? Not sure, but it works perfectly and I prefer having the server do the majority of the work. I think I might also add some 301 in the redirected header. May Digg dig its own hole.
And on a side note, have a laugh.