Looking for suggestions - underrated ps3 games.

Every single Ratchet and Clank game. All of them.

also Katamari.

NIER

Disgaea, of course.
assuming you're into SRPGs

Eternal Sonata
Last Rebellion
Catherine
RAGE
Trinity Universe
Disgaea 3
Disgaea 4
Nier
Kingdoms of Amalur: Reckoning
Hunted: The Demon's Forge
White Knight Chronicles I + II
Folklore
Asura's Wrath
Dante's Inferno

Thanks for the suggestions!

everything from Ninja Theory is brilliant and underrated (Heavenly Sword, Enslaved and DmC)

edit: also both Darksiders games are very underrated and very good

The Getaway is a good one, But it would be under ps2 ports if they have it on psn.

Unknown or underrated:

Valkyria Chronicles

Enslaved - Odyssey of the West

Ratchet and Clank series

Singularity

Split/Second

Popular but good:

Uncharted series

Infamous series

Kane & Lynch: Dead Men
Condemned 2: Bloodshot

I just got a PS3 too. Only got Dynasty Warriors 8 which is absolutely awesome. I'd recommend having a look at the PS2/PS1 downloadable games on PSN.

A lot of people hated it but I enjoyed the fps Haze, it was a little buggy and the reviews hated on it but I'd say it was a solid fps with a nice gimmick. Also the satire of the story completely went over most of the reviewers' heads.
I'd also recommend the co-op, if anyone is still playing it.
Formula One Championship Edition is also a nice racing game.