Unlockables:

Alternate Ex. Files screen music
Beat the game and make a "Clear game" save. Use this save to load the he Ex. Files screen, and you can enjoy some different background music.

Monster Encyclopedia
EX File Keys 1, 2 and 3
Opening and Ending Movies
EX File Keys 4, 5 and 6
Character Encyclopedia
EX File Keys 7, 8 and 9
Character Voice Library
EX File Keys 1, 4 and 7
EX New Game
EX File Keys 2, 5 and 8
EX Status View
EX File Keys 3, 6 and 9