Network (a performance for which he won the Academy Award for best actor). It's amazing to realize that the movie came out 30 years ago.
The segment embedded here is the shortest one I could locate on YouTube. I suspect with the way the U.S. economy and world geopolitics are going, this classic movie scene may be more relevant in the coming year.
Addendum: Originally posted in January of 2008. Reposted now to pair up with the Dylan Ratigan rant above.