Search for disgaea and you'll find the anime OP and ED. And there are some songs from the Disgaea game in the game section. Go to the "Playlist Info" and there's a link to game-related songs.
I'll search around for some of that other stuff.
EDIT: Found them, largely thanks to the video game music expert living in my basement.
Ai no Uta / Strawberry Flower / From the GameCube game "Pikmin"
Kaze no Ne / Yae / Opening theme from the GameCube game "Final Fantasy Crystal Chronicles"
REDEMPTION / Gackt / "Dirge of Cerberus" from the PS2 game "Final Fantasy 7"
Sinful Rose / YOKO / Opening theme for the PS2 game "Disgaea 2: Cursed Memories"