Here's the list of movies with at least three mentions as of 1100 MDT 08 June 2011.
Sorted in descending order by number of mentions, then alphabetically.

12:
Shawshank Redemption, The

10:
Princess Bride, The

7:
Godfather, The
Good Will Hunting
Matrix, The

5:
Forrest Gump
Groundhog Day
Love Actually
Pulp Fiction
Wizard Of Oz, The

4:
Back To The Future
Breakfast At Tiffany's
Ferris Bueller's Day Off
Fight Club
Gladiator
Ocean's Eleven
Serenity

3:
Amelie
Anchorman: The Legend Of Ron Burgundy
Big Lebowski, The
Bull Durham
Citizen Kane
Field Of Dreams
Garden State
Goodfellas
Great Escape, The
Hitch
Independence Day
Office Space
Pride & Prejudice
Sixteen Candles
Sound Of Music, The
Thomas Crown Affair, The
Zoolander