Hit PSN for demos. There are demos for every Move title so far as I know. That'll keep you busy on the Move front and allow you to get a feel for other potential titles.
Heavy Rain Move also has a demo, too, so you can try that as well.
I'd then get demos for the best PSN titles, Flower, etc. as well as any other demos that you think appeal.
That should keep you going until you decide what you actually want to buy.
For me the "must buy" PS3 title is Little Big Planet. But then I think it's the best new IP in the last 10 years. Mind you... I'm right!
Obviously, for you that means LBP2 as it's going to be near enough backwards compatible so you'll get the fantastic LBP2 plus access to near 3 million user created levels.
Unless you don't like the look of them or their genres I'd strongly suggest you check out the best PSN titles for purchase, too.
Wipeout HD
Flower
Super Stardust
Pixel Junk Monsters, Shooter, etc.
and others are all really great games and a cost effective way to expand your library. Wipeout looks fantastic in 1080p and while a download title is actually one of the best looking titles to show off a nice TV. It's also a great high speed racer, too.
Try to be reasonable... its easier than you think...
