Probably the most ambitious and impressive metal video ever : http://www.youtube.com/watch?v=j8bUs0eqHYY
All of them : http://www.youtube.com/results?search_query=tool&search=
i like these...cba to post more right now....
Legion Of The Damned - Werewolf Corpse
http://www.youtube.com/watch?v=1251940MdQs
Decapitated - spheres of Madness
http://www.youtube.com/watch?v=vfRT5FZYI10