As ryandubbz said, you can't go wrong with Dead Space (or 2, for that matter). Here's some worth a look...
Bio Shock 1 or 2
Uncharted 1 or 2 (or 3 next month.....if you wanna play 3's online component for free till 11/1/11, hit up Subway and get a large soda. Each cup has a code to download the full mp game. )
Resistance 1, 2 or 3
Killzone 2 or 3
COD: MW2 or Black-Ops (or MW 3 next month)
Battlefield: BC 2 (or Battlefield 3 later this month)
Resident Evil 5
Warhawk (online only game, or Starhawk which is coming out soon)
Hope that was helpful, and you enjoy shooting some people in the face.
