Comedy Central's list of the greatest 100 is here:
http://www.listology.com/list/comedy...ndups-all-time
Here's another list:
http://www.buzzle.com/articles/great...comedians.html
I forgot guys like Carson and Letterman, although a monologue really isn't the same as doing 30 minutes of stand up.
Russell Peters, Bobcat Goldthwait and Emo Phillips all deserve mention as well. Bobcat is hilarious at standup, especially if you've heard his act lately.