Please, take a look at Wipeout HD and its expansion Fury.
It´s a great game, very entertaining and commonly left apart because of its nature of downloadable game (yes, I know that there´s a physical retail version but its quite difficult to find a copy). As far as I´m concerned, it´s one of the best racing arcade games of the generation and a must buy if your consider exclusive-only games for the Playstation 3 family.
Apart from that, Valkiria Chronicles it´s a must-buy if you love tactic-RPG. The best way to describe it is that it´s some kind of XCOM, with a stronger story component and no strategical part, but similar in how the battles are engaged. As with Folklore, it´s a early game in the platform and very enjoyable.
Probably a nigthmare for many people, "Lair" (yes, Lair) with the patch that allows control with analog sticks it´s a game very arcadey in nature, replayable and a-bit-less than awful, as the metacritic score announces. Even as an archeologic return to the ancient past of the console must have an opportunity. Finally, Heavenly Sword it´s brief, well animated in its sequences and to some extent enjoyable.
These are some of the rarest exclusives of the console. On the other side, I can hardly recommend other ancient exclusive (Haze) because definitely here critics and I are in line: it´s a weak game - some will dislike this opinion, for sure, but technically speaking it´s fair, and the playability isn´t very inspired.
Good luck with your new PS3.