Don't think I've watched the Dude from start to finish, but have probably seen the whole thing in bits and pieces. Never seen Scarface, Bridges of Madison County (proud of that one), Raging Bull, On The Waterfront, and probably a good couple of dozen more.
I've probably only seen about a third of the AFI Top 100 films of all time.
http://www.afi.com/100years/movies10.aspx
There's several I wish I'd never seen, as well.