So the Playstation Store has a load of games for $5 right now that you should definitely check out. There are also quite a few pretty terrible games in there but I will let you be the judge of what is what.
For starters you could pick up: Bioshock, Bioshock 2, Red Dead Redemption or GTA IV. You could do a whole lot worse for five bucks. Which brings me to Duke Nukem Forever and Kane & Lynch 2... I mean, just don't bother. I know that it is only five bucks but you can do better than that. You are better than that. One game which absolutely stands out for me is Spec Ops: The Line. If you haven't already played this then do yourself a favour and pick it up, you won't regret it.
While Bioshock, RDR and so on are great games and I highly recommend them, Spec Ops deserves special praise for it's own take on the shooter genre. It is based on the book "Heart of Darkness" and is set in modern day Dubai. It follows a group of soldiers and their decent from cocky, humorous soldiers to confusion to anger to hopelessness to sadness and to other stuff that I don't want to spoil.
Really, this is a $5 buy that might give you PTSD, but you won't regret it. (or ever look at yourself the same way)
"Do you feel like a hero yet?"