I am semi trying to collect all the domestic PS2 music type games, so I'll first start by saying what ones I have.

Parappa the Rappa 2
DDR Max
DDR Max2
DDR Extreme
DDR Extreme 2
Technic Beat
Amplitude
Frequency
Taiko Drum Master
Guitar Hero

Now, these are the ones that I'm pretty sure are the rest of the music games

Guitaru Man
REZ
American Idol
Karaoke 1-3 (three so far, right?)
Karaoke Revolution Party
Get on da Mic
Britney's Dance Beat
Unison
MTV Music 2-3
eJay Club World
Funk Master Flex: Digital Hitz Factory
Mad Maestro!
Space Channel 5 part 2
Ephemeral Fantasia (?)
In the Groove
(In 2006) beatmania