Current List: Recent additions in bold.

Amplitude
Another Century's Episode
Another Century's Episode 2
Another Century's Episode 3: The Final
Arc The Lad: End Of Darkness
Arc The Lad: Twilight of Spirits
Burnout 3: Takedown
Capcom vs SNK 2
Dark Cloud 2
DDR: Extreme
DDR: Extreme 2
DDR: Max
DDR: Max 2
DDR: Party Collection
DDR: Supernova
DDR: Supernova 2
DDR: X
Devil May Cry 1
Devil May Cry 2
Devil May Cry 3
Espgaluda
Final Fantasy 10
Final Fantasy 12
God of War [DVD5/9]
God of War 2 [DVD5/9]
Gran Turismo 4 [DVD5/9]
Guitar Hero I (track list)
Guitar Hero II (track list)
Guitar Hero II: Sex, Drugs and Rock'n Roll (track list)
Guitar Hero III (track list)
Guitar Hero III: Anubis (track list)
Guitar Hero IV - World Tour [DVD5] (track list)
Guitar Hero Encore: Rock the '80s (track list)
Guitar Hero: Aerosmith
Guitar Hero: Metallica [DVD9] (track list)
Ico
In The Groove
In The Groove 2 (Beta)
Ico
Jak and Daxter
Jak and Daxter 2
Jak and Daxter 3
Katamari Damacy
Kingdom Hearts
Kingdom Hearts re: Chain of Memories
Kingdom Hearts 2
LEGO Star Wars
LEGO Star Wars II: The Original Trilogy
Manhunt
Manhunt 2
Marvel vs Capcom 2
Max Payne
MGS3: Subsistence 1of3
MGS3: Subsistence 2of3
MGS3: Subsistence 3of3
Okami
Prince of Persia: Sands of Time
Prince of Persia: Warrior Within
Prince of Persia: The Two Thrones
Ratchet and Clank
Ratchet and Clank: Going Commando
Ratchet and Clank: Up Your Arsenal
Ratchet: Deadlocked
Resident Evil 4
Rez
Rock Band [DVD5] (track list)
Rock Band 2 [DVD5/9] (track list)
Rock Band Track Pack Volume 1 (track list)
Rock Band Track Pack Volume 2 (track list)
Rock Band Track Pack ACDC (track list)
Sega Superstars Tennis
Shin M--: Persona 3
Shin M--: Persona 4
Shadow of The Colossus
Singstar 90s
Singstar Legends
Soul Calibur II
Soul Calibur III
Spartan Total Warrior
Star Ocean 3
Star Wars: The Force Unleashed
Suikoden 3
TimeSplitters 3 Future Perfect
Tony Hawk's Proving Ground
Twisted Metal: Head On
We Love Katamari

Multiplayer/Party games:

Burnout 3: Takedown - Racing, crashing, and crash racing.
Capcom vs SNK 2 - Two player fighter.
Espgaluda - Two-player co-op scrolling shooter.
Freedom Fighters: The Battle for Liberty Island - Two player co-op. Up to four player split-screen deathmatch.
Killzone - "contain six team arenas that can be played online or offline, alone or with a friend. If you don't have a friend to play with or you have a friend who spends every waking hour playing and continually frags your sorry behind, every ARENA can be adjusted and played solo with AI bots, spawning, time limits, and more, depending on your skill level."
Marvel vs Capcom 2 - Two player fighter.
Ratchet & Clank Up Your Arsenal - Up to four people offline; Up to eight online.
Sega Superstars Tennis - Sonic the Hedgehog Tennis.
Soul Calibur 2 - Two player fighter.
Soul Calibur 3 - Two player fighter.
Star Wars: Battlefront - PS2 online play lets you battle against 16 players over the Internet or 32 players connected via LAN.
Star Wars: Battlefront 2 - Possibly similar to first game.
Time Splitters 2 - Up to four players offline. Over LAN play possible. Also, map creation.
Time Splitters: Future Perfect - Two-player co-op. Online and offline multiplayer. Also, map creation.