Despite the many people who have already contributed, I can't help myself.  Since you said exclude the obvious, that may mean that the Godfather, Citizen Kane, Casablanca, and Lawrence of Arabia are out.  I also don't think anyone would appreciate Star Wars in this crowd.  So here goes, somewhat personal, but excuse me if I pick a popular film.
1. All Quiet on the Western Front
2. 2001:  A Space Odyssey
3. Pulp Fiction
4. Apocalypse Now
5. Ordinary People
6. The Shining 
7. Schindler's List
8. Days of Wine and Roses
9. Dances With Wolves
10. Singin in the Rain
There are many excluded, but thats a start.  Just for the record Kane is the greatest ever.