There are lots of good games ....I would suggest you these :
Wipeout Pulse
God of War :Chains of Olympus
Final Fantasy VII Crisis Core
Lumines
Crush
Disgaea Hour of Darkness
Syphon Filter Dark Mirror and Syphon Filter Logans Shadow
Final Fantasy Tactics War of the Lions
Daxter
Sega Genesis Collection
Out Run 2006
Virtua Tennis 3
Tekken Dark Ressurrection
Ace Combat X
Tales of Eternia
Burnout Revenge or Burnout Dominator
Everybodys Golf 2 (with online play)
PES2009
Marvel Ultimate Alliance (fantastic version)
With these you have covered most game genres .....