Meanwhile, at JPN's PS+...
Also, there are few gems in the "123+ Game Archive games on PS+". Especially if you're a Nippon Ichi fan.
-Marl Kingdom's Doll Princess (Rhapsody Musical Adventure)
-Little Princess ~Marl Kingdom's Doll Princess 2~
If you know Japanese (and have played Disgaea in JP), these two will come as a rather nice find. Though I'd recommend the DS version of the first game, since they apparently changed a lot of the annoying stuff in the PSX version (encounter rate, battle system). Too bad the third game is a PS2 game that didn't get a PSN release.
Little Princess is goddamn awesome, though. System-wise, it doesn't feel an old game. Comparatively, LP is leaps beyond the first game. From its story-telling to its musicals to events to characters and character interactions. AND OH MY GOD. The sprite work in this is made of LOVE. Whether it's NPC sprites or the one for musicals use, you can feel that there's a lot of work carefully put into them.
They also recently added Legend of Dragoon to it.