I always loved his "Parliamentary Office Coup d'Etat" video where he exhorted Canadians to rise up and slay the Harperites!

The shaky camera, "bottom of a wishing well" audio quality and quavering delivery really rallied people to that putsch. 

The only thing that would have helped would have been to have his dog Kyoto discretely relieving himself on camera right while Dion spoke.