I am severely bummed about this news. He might have been my favorite comedian of all time. I distinctly remember when we got a copy of Live at the Met (one of the best comedy albums ever) in my first or second year of college. Practically the whole dorm would listen to the entire tape over and over. I've probably heard it 100 times.
One time in a lecture hall Biology class, where probably a quarter of the class was from our dorm, the teacher was describing some sort of algae and I burst out with, "This shit is green!" It took a couple of minutes for everyone to stop laughing, and I almost got kicked out as well.
In case you've never heard that masterpiece of a show, this is the relevant part (apparently I can't figure out how to get it to start at 1:15, so just skip to there):