me new in ps3 just bought it just before christmas. so far i have:
MW2 - the best game so far
rainbow vegas 2 - 2nd best, but comes a very close 2nd
operation flashpoint - meh

i have a wii too, and there is where my band game collection resides. so, if i consider the wii, these are also my fav that i own (can be found on ps3 too):
1. guitar hero world tour
2. rock band 2
3. guitar hero smash hits
4. guitar hero 5
5. guitar hero metallica
6. rock band beatles
all mainly on drums, although i do grab the guitar for a quick fix. i only sing on beatles, coz there is harmony singing.

i promise myself only 1 new game per month. so i can keep my game purchases on budget. besides, it really takes me 1 whole month to complete a game. not so hardcore....and not by choice

bought mine last nov 09.
let me see:
1. mw2
2. killzone2
3. bad company2
4. uncharted 2
5. band hero 2 - just kidding
i don't think i add any for awhile. coz i feel guilty spending too much to frequently