Gran Turismo 5 and Guitar Hero 3, Kaos wait till you watch a Blu-Ray movie on the Ps3 its amazing. I have bought several Blu-Ray discs used from ebay for around 10 dollars.
I will quote my wife on that (we haven't tried one yet, BTW):
"BluRay, SchmooRay. It's a freaking movie."
As for the games, I have RockBand. Would love to play some of that online. I don't know how to create friends and all that horsemanure, but if somebody could send me their online deal or whatever so I could invite them to play in my fake band I would do that. I suck at it. Can do fine on medium, but once it gets to hard or expert (except on some songs on bass) I fail.
I have GH (1,2,3 and 80s) for PS2. Debated getting GH3 for PS3, but am so used to having the drums that it seems kind of limiting. I do like the GnR songs on GH and the fact that I could download Slither is enticing.