Ya know, I'm taking a look at this. Some things I know I didn't count towards that list are some of the demos. I'm not sure if you count those, but if you do then you can add:
Pokemon Colosseum Bonus Disk
Resident Evil 4 Demo
Starwars Rebel Squadron III Demo
Soul Calibur II Demo Disc
Naruto Clash Demo Disk
If we added those that would put my list at 550.
If you counted all the double and triple packs you could add:
Resident Evil Anniversary 3 Pack
Resident Evil Pure Evil 2 Pack
Super Monkey Ball 2 Pack
Sonic Adventure 2 Pack
Sonic/Monkey Ball 2 Pack
Then your at 555... :P
Some things that ARE already in the list are:
Pac Man Vs.
Pac Man Vs. / Pac Man World (This is a Player Choice Only game)
Nintendo Gamecube Preview Disc
I'm not sure if you count those or not, but I did.