The Original AFI Top 100 from 1998:
http://www.afi.com/100years/movies.aspx
From that list, the five highest that I haven't seen are:
- Singin' in the Rain
- Sunset Blvd.
- All About Eve
- Chinatown
- The Grapes of Wrath
The Updated 10th Anniversary List from 2007:
http://www.afi.com/100years/movies10.aspx
I don't do as well on that list:
- Singin' in the Rain
- Vertigo (I might have seen this, I'm not sure)
- City Lights
- The Searchers
- Sunset Blvd.
I've seen so many shows that pay tribute to Chinatown, that I feel like I've seen it ("She's my sister AND my daughter!"). I really should watch it some day.
I also need to watch more Hitchcock.